F6IRF hamradio contesting

This blog is dead !

2009-08-29T08:35:00.002+02:00

You may have noticed that this blog is dead. Although it may not be definitive, my interest is for the moment attracted elsewhere... However the archives are still here and provide many hours of reading on various topics. A simple way to start is to consult the "best of" which provides a quick summary and list the articles in the right order... Good reading !

No comment !

2008-12-13T16:26:00.000+01:00

No comment... comme ils disent sur euronews !

l'humeur du jour...

2008-12-08T11:19:00.001+01:00

CQWW CW 2008 - M/S @TM6M - OM8A EU-Leader ?

2008-12-05T08:19:00.005+01:00

The OM8A 3830-claimed score did not came as a real surprise, but shows what remains to be done to expect a first European M/S place... a lot !
Once again, the biggest gap is on 80m very weak both in QSO's and mults. 160 and 10m come after, while the results on 15 and 20 are not that bad. 40m is almost competitive, just missing 10~15 multipliers...

CQWW CW 2008 - M/S @TM6M - Known M/S claimed scores

2008-12-03T17:50:00.007+01:00

This year for the CQWW-CW Nico (F5VIH/SV3SJ) and myself responded to the TM6M (F6KHM) invitation. A long trip by road (2300kms), but a lot of fun ! Following are the first known raw-claimed European results for the M/S HP category. Above are the top known EU-claimed scores. It is quite obvious that the multipliers are our weak point, while the QSO-points is our strong one... Above are the compared EU-M/S 3 known top-scores, by band. Our weaker band is 80m, while our strong band is 15m. In general, our multipliers deficit is stronger on the low bands.

Low-band DX'ing: The high-angle mode hypothesis - G0KYA contribution

2008-11-25T09:52:00.008+01:00

In my previous post, I gave a few links mentionning the "high angle mode". I found extremely interesting G0KYA's paper "the twilight zone".
This is the introduction: Steve Nichols G0KYA, of the RSGB's Propagation studies Committee, believes that propagation around sunrise and sunset is not fully understood. Here he outlines the mechanisms behind grey line and other twilight propagation modes and a research project to help us understand them.
And a particulary interesting paragraph Now imagine a radio wave hiting the ionosphere at about 75-85 degrees to the earth - a near vertical incidence wave (NVIS). Below the critical frequency, it would be returned. At some frequency close to fof2 it could be refracted through a large angle and could end up travelling almost parallel to the earth, giving a very long first skip distance. This is the condition for the Pedersen or critical ray, discovered in 1927, characterised as being high angle, long distance and close to and probably above the fof2 frequency. As there would be no intermediate ground hops the signal strength could be very high indeed.

Following this reading, I exchanged a few emails with Steve (one of them, reproduced here with his authorization)
Hi Patrick, Thank you very much for your e-mail. I have had a quick look at your blog and it is very interesting. Your message was actually very timely as I have been looking at WSPR as a greyline beacon tool, but had put it to one side to concentrate on other things - I will pick it up again! Here are some thoughts and observations that might be useful.
1. VOACAP is not very good at predicting openings below about 5MHZ. It was never intended for this and is usually very pessimistic. W6ELProp is better.
2. You are quite right - it doesn't take into account sunrise enhancements I did some work on signals from VP6DX into the UK on 80m and using VOACAp looked at the number of modes (hops). It showed clearly that there are more modes around sunrise and the radiation angle goes higher. I can send you this if you want. I am therefore convinced that greyline has more to do with higher angle signals due to ionospheric tilting and multiple modes than the old "D layer not illuminated/F layer illuminated" model.
This also explains why you get good greyline openings at right angles to the terminator.
Thanks for thinking of me.
Steve G0KYA
RSGB Propagation Studies Committee
http://www.qsl.net/g0kya/
You will find other articles and powerpoint presentations on Steve page, definitely a "must read" for whoever is interested by those phenomenas (the above pictures are from Steve presentations). Steve's VP6DX presentation is available as a PDF.
By the way, the "high angle mode" has a name: The Pedersen Ray... and nothing new, since it was discovered in 1927...

Low-band DX'ing: The high-angle mode hypothesis - part 2

2008-11-22T11:18:00.010+01:00

Following are the results of a quick test done this morning on K1JT 80m WSPR beacon. As for the previous post, I was using 2 antennas, my K9AY pointed NW and a magn loop, this time oriented NE, so roughly 90 degrees away from Joe's direction. The magn loop pattern at 90 degrees is particulary interesting because its response at low angle is minimum.
Following is the plot of the measured SNR's around sunrise. Although the mag-loop is 90 degrees away from the TX-direction, it still takes the advantage just after sunrise (SR at 0645z). (you may click on the plots to enlarge them). The above plot is for the SNR's measured on K1JT WSPR-beacon on 2 antennas , a K9AY oriented NW and a mag-loop oriented NE. Despite the limited number of points, and the mag-loop orientation, the trend is clear: Just after sunrise the mag-loop provides slightly better SNR's than the K9AY, which is likely to confirm the "high-angle propagation mode hypothesis".
This plot shows the pattern of the magnetic-loop, for various elevation angles. The front to side ratio goes from 12dB at 5degrees elevation (red pattern) to 1dB at 60 degrees elevation (blue pattern). The orange pattern is for 20 degrees, while the purple is for 40 degrees.
This plot shows the compared patterns of the K9AY and the magn-loop turned 90 degrees away from the transmitter direction. In blue the magn loop pattern a 60 degrees, in light blue at 20 degrees. In red the K9AY pattern at 60 degrees, in purple at 20 degrees. The respective max gains being almost equal, the 2 patterns cross at an elevation angle of approximately 60degrees. Below 60 degrees, the K9AY should provide better SNR's while the Magn-loop takes the advantage at angles higher than 60 degrees.

IMHO, those plots clearly show that a high angle propagation mode appears at sunrise. It would seem, still for this particular path at this particular moment, that the take-off angle is at least 60 degrees, or higher. This explains why stations using low horizontal antennas, get "better than expected" results on a few DX-paths, although a low horizontal antenna (below 1/4 wl) has a poor efficiency due to important ground losses. The little difference shown in the earlier published plot of DG0OPK signal (using a G5RV at 5m) vs mine (using a 1/2 wave vertical over a good soil), as received by VK7KRW on 40m long-path, may also have an explanation when looking at the "high angle mode" hypothesis.

For information I also looked at the SNR's measured on WA6MTZ (CA) 80m signal. On this particular 9300 kms path, there is no obvious benefit provided by the magn-loop. However as I have only a few spots, it might be too early to make definitive conclusions... so, more to follow !

Addendum: I experienced the same phenomena on YA/T61AA signal at sunset..
If you are interested by the topic, I found 4 online articles which mention the phenomena: By ZL1BPU, by G3CWI, by G0KYA and from antennex by ON5AU

Low-band DX'ing: The high-angle mode hypothesis

2008-11-20T12:18:00.012+01:00

Following the publication on this blog, of the VOACAP articles and the comments received from AB7E and OH6BG, my friend Seb F8CMF pointed me an old K3LR post on the "top-band reflector". Here is the post (reproduced with Tim's authorization).
=========================
Topband: Low RX Dipole
========================
*To*: >
*Subject*: Topband: Low RX Dipole
*From*: k3lr at k3lr.com (Tim Duffy K3LR)
*Date*: Mon May 5 20:52:53 2003
Hi Gale!
It all depends on what other antennas you have. I have had up a 14 ft
high 1/2 wave dipole on 160 for many years. It has always impressed me
as a high angle antenna which limits its prime effectiveness to gray
line use. I also use it in tandem with other antennas and the MFJ
receive antenna noise canceling W8JI magic box (also an effective
antenna phasing unit). My low dipole's claimed fame was a sunrise QSO
with KH2. No other antenna (1100' beverage, vertical array, etc.) could
hear the KH2, but he was 569 on the low dipole.
73!
Tim K3LR
=======================
Remembering that I received ZL1RS only on the magn-loop, this post interested me very much. Taking the opportunity of the "WSPR 80m Special Activity Day" I quickly setup a diversity receive test, using 2 receivers, one connected to the K9AY loop, oriented NW and one to the magn-loop (roughly E/W).

The compared patterns of the K9AY and the magnetic loop. Considering RX antennas, it should be made abstraction of the respective Gains and focus on the RDF. According to K7TJR tables, the RDF of the K9AY considered at 20degrees elevation is 7.2dB, vs 4dB for the magnetic loop, thus a 3.2dB advantage for the K9AY. Of course considering a higher angle, the difference will turn to the magn-loop advantage, as it exhibits a pattern more favorable to NVIS.
The plot shows the SNR's measured on 80m from 9 NA-stations during 2 nights on 2 RX-antennas. Over 500 spots, were used. By distance order VE1VDM (5205kms), W1BW, W1XP, K1JT, WD4KPD, W8LIW, KI4MTI, vE5MU, K4MF(7572 kms). In the middle of the night, the K9AY provides some 5dB average better SNR than the Magnetic-loop wich suggests an elevation angle lower than 20degrees.

The same as above, but focusing on the morning. The fact that the magn-loop takes the advantage near sunrise seems to be a confirmation that some "high angle" mode occurs at this particular moment and not only on paths following the grey-line. The respective antenna patterns suggest an vertical angle >45 degrees. A more "radical" NVIS antenna (like the "cizirf-special") has to be tried to confirm this hypothesis.
Last but not least: for the path F6IRF to W8LIW, VOACAP suggest a vertical angle of 8 degrees, with a peak at 15 degrees in the middle of the night. Once again the VOACAP-model is obviously far away from the above observations. As Dave AB7E mentionned "It (voacap) is especially weak in predicting the effects of takeoff angles /// I'm convinced that much of gray line propagation is chordal hop, which is supported by the comments from K3LR and others (as well as my own observations) that high angle antennas often work better for such openings. When you draw a picture of the earth showing an F2 gradient at sunrise/sunset it is easy to see why that would be true."
What seems to show the above, is that "the high angle mode" does not only concern long DX-paths along the grey-line (such as F<>ZL) but also shorter distances DX paths.

The VOACAP mystic, an interesting comment...

2008-11-18T06:50:00.006+01:00

I received the following emails from Dave AB7E (reproduced here with his authorization). Think he is saying interesting things...Hi, Pat. Wow ... what a rigorous and interesting analysis. Very impressive.
My first reaction, though, is that an antipodal path (ZL-F) is possibly not the most valid for comparing VOACAP predictions to real life propagation. VOACAP assumes a single direct path (either SP or LP), whereas the actual path for an antipodal target could be almost any direction. VOACAP might render its calculation based upon a path over Asia while the actual signal might not take that route at all. As a real life example, my Optibeam OB16-3 has a pretty narrow beam width on 20m (I can easily hear the difference in 20 degrees of beam heading), yet when working VQ9RD recently (close to antipodal for me), it was almost impossible to find a "best" beam heading within about a 70 degree spread. VOACAP, of course, is based upon heaps of experimental observations taken decades ago, with extrapolations based upon theoretical models of the ionosphere. It doesn't even come close to being a valid predictor of real-time conditions, a fact that the authors were very quick to point out but which hams have conveniently ignored.
It is especially weak in predicting the effects of takeoff angles, which can have a large impact. So overall I'm not surprised that your analysis would find large discrepancies between predicted and actual SNRs, but I suspect that the results would have been closer for a non-polar path of roughly 1/3 the circumference of the earth instead of 1/2. 73, Dave AB7E

pat_f6irf wrote: Yes David agree... I think Jari that OH6BG summarized it very well in the part 4. The purpose of this article was to draw the attention of contesters and DX-men, on the fact that VOACAP is not suitable at all for low-band DX'ing... What the designers accept, but most hams ignore (including me b4 looking at it !); see http://www.voacap.com/lowband.html
Even the 10degrees vertical angle forecast may be wrong...

Hi again, Pat. Yes, I think VOACAP is quite poor for low band use, especially since so much of it is gray line dependent. I'm convinced that much of gray line propagation is chordal hop, which is supported by the comments from K3LR and others (as well as my own observations) that high angle antennas often work better for such openings. When you draw a picture of the earth showing an F2 gradient at sunrise/sunset it is easy to see why that would be true. I don't think that VOACAP even considers chordal hop propagation mechanisms at all. I certainly hope you keep up the excellent work, and I think the diversity experiments should be very interesting as well. 73, Dave AB7E

Thanks Dave...
Your email reminded me that already ZL at long path (audio recording) was something for my "Cizirf-special" antenna, which was not designed to be a DX antenna.
Promised, I'll come back with the same type of analysis for shorter distance paths.

By the way, I have updated the blog "best of" , an easy way to find articles...

The VOACAP mystic, a summary...

2008-11-17T13:32:00.006+01:00

Why "the VOACAP mystic" ?
I would recommend to read this as a starter

Once done and for those who may have missed the early posts. Following is a summary of all the posts published on the a/m topic. It will allow to read them in the right order...
- VOACAP vs WSPR reports part 1 (study of a 30m transatlantic path)
- VOACAP vs WSPR reports part 2 (study of a 30m transatlantic path)
- VOACAP, the end of the myth ? part 1 ( study of a F<>ZL 40m path)
- VOACAP, the end of the myth ? part 2 ( continuation of the study of the F<>ZL 40m path)
- VOACAP, the end of the myth ? part 3 (study of a 40m long path F to VK7 + my temporary conclusions)
- VOACAP, the end of the myth ? part 4 (back to F<>ZL short/long path, OH6BG calculations and opinion)

May not be complete: I am still consolidating data on 80m F<>ZL path, which may lead to strange conclusions on the required take-off angle. Now that I have improved my knowledge of Voacap, I may also come back later on shorter distance paths. So, stay tuned !

Please note: So far these articles, exist only as "blog posts" (I like the spontaneous day to day blog form). Of course they may be made available for publication in a more conventionnal support, or public presentations if some interest is expressed. In any case, please contact me for any adaptation/translation...

VOACAP reliability, the end of myth ? part 4

2008-11-17T11:36:00.004+01:00

Following the publication of the series of articles on VOACAP reliability, Jari, OH6BG (voacap.com) sent me the following email (reproduced here with his authorization). I have just underlined the key-elements.
Hi Pat,
Kari OH2BP wrote to me today pointing out your monitoring results vs. VOACAP predictions blog at http://f6irf.blogspot.com/. A very interesting reading indeed, and a constant reminder for all of us that predicting HF propagation is indeed more of an art form than an exact science, hi!
I have made similar monitoring sessions with Faros on July 2007, and, on 14 MHz, VOACAP miserably failed to predict circuits from Finland to the United States in the middle of the night. I reasoned then that the twilight hours that prevail at that time of the year here in the North generate many hours of signal-enhancing "sunset" effect at this end, which VOACAP simply cannot see.
Below I gathered my personal observations, which can perhaps help you in your endeavour of tackling the issue in hand...
1. A quick run reveals that the use of the older IONCAP absorption model can, in your case, give up to 15 dB better SNR/SDBW values over the more conservative "Normal" absorption model, used in your calculations.
2. You must not only look at the predicted SNR values, please note also the predicted median Signal Power values, S DBW.
3. You must not only look at the predicted median values of Signal/Noise and Signal Power. Calculate also the predicted upper decile (10%) values that tells you the probability values for SNR and S DBW on 3 days (10%) in a month. The SDBW10 values specifically suggest an extremely poor, but probably distinguishable (if the real Noise Power is not too overwhelming), signal at the time periods that have been monitored, although the values themselves are extremely conservative, but to me, a right tendency can be seen. Formulas: SNR10 = SNR + SNR UP SDBW10 = SDBW + SIG UP
4. I have understood that extremely long circuits (such as this, far far beyond 10,000 km) can be troublesome for VOACAP and probably the predicted values are of a more conservative note. Therefore, I am pretty amazed at VOACAP being able to figure out the correct tendency anyhow.
5. In addition, I can only speculate that perhaps the greatest influence for the "better-than-predicted" monitoring values lies in the fact that the time periods of monitored best reception on 7 MHz seems to occur approximately at ionospheric sunset/sunrise on either side of, or along, the circuit. As far as I know, VOACAP is not able to take into account the signal-enhancing sunrise/sunset effect, which I can also confirm by my own monitoring on 14 MHz.
73 Jari OH6BG/OG6G

Attached to Jari's email was the run output table which I have plotted here vs "the observed average" over near to 3 weeks period (plot published in article part 2)This plot has been made using OH6BG run prediction table. It uses the old IONCAP absorbtion model, assumes Isotropic antennas at each end of the path, and a very quiet man-made noise level of -155dBW/Hz at 3Mhz. The purple curve is the "upper decile" (3 days per month) while the blue one is the SNR (as shown earlier equivalent to SNR50, so 15 days per month). The red curve is an averaged measured value over a 3 weeks period.

Following are the parameters that Jari used:

SHORT PATH: F6IRF to ZL2TLD, using IONCAP absorption model
CCIR Coefficients ~METHOD 30 VOACAP 08.1023I PAGE 1 Oct 2008 SSN = 7. Minimum Angle= 3.000 degrees f6irf zl2tld AZIMUTHS N. MI. KM 45.80 N 6.00 E - 40.96 S 175.59 E 61.06 306.11 10267.9 19014.6 XMTR 2-30 + 0.0 dBi[samples\SAMPLE.00 ] Az= 61.1 OFFaz=360.0 0.001kW RCVR 2-30 + 0.0 dBi[samples\SAMPLE.00 ] Az=306.1 OFFaz= 0.0 3 MHz NOISE = -155.0 dBW REQ. REL = 90% REQ. SNR = 4.0 dB
LONG PATH: F6IRF to ZL2TLD, using IONCAP absorption model
CCIR Coefficients ~METHOD 30 VOACAP 08.1023I PAGE 1
Oct 2008 SSN = 7. Minimum Angle= 3.000 degrees
f6irf zl2tld AZIMUTHS N. MI. KM
45.80 N 6.00 E - 40.96 S 175.59 E 241.06 126.11 11345.0 21009.3
XMTR 2-30 + 0.0 dBi[samples\SAMPLE.00 ] Az= 61.1 OFFaz=180.0 0.001kW
RCVR 2-30 + 0.0 dBi[samples\SAMPLE.00 ] Az=306.1 OFFaz=180.0
3 MHz NOISE = -155.0 dBW REQ. REL = 90% REQ. SNR = 4.0 dB

In a later email Jari wrote:
Although I am by no means a specialist of low-band propagation, my little experience tells me that enhanced signal levels and openings on lower bands can be observed 1 to 2 hours before sunset and similarly 1 to 2 after (if not even longer) hours after sunrise. And both the stations need not be on the terminator zone, "greyline"... This particular case with ZL2 could fit into this framework. When it comes to using VOACAP for predicting propagation on lower bands, I firmly believe that predictions on 80M, not to talk about 160M, are simply doomed to fail for any longer path... George Lane writes about this at http://www.voacap.com/lowband.html as follows, "... George Haydon said there was very little data below 4 MHz but there was some for short paths that did go down to 2 MHz. So they modeled a fit to those cases. Risky, but it has proven to give good results for Near Vertical Incidence Skywave (NVIS) situations. ..."
So, trying to use VOACAP to predict low-band DX propagation is asking for trouble. Maybe you can get better results just by simply looking at sunrise/sunset maps! hi.

Many thanks Jari for your contribution... I think that the message is clear !

back to "another low band vertical"

2008-11-14T07:59:00.006+01:00

13 monthes ago, I published a complete description of my "low band" vertical. This antenna continues to surprise me every day by the reports I am getting worldwide. Just as an example, I recently had several bilateral WSPR-exchanges with ZL1RS on 80m long path using 5W. This is what says Larry W8LIW (OH) " As for the spots of your station, sometimes I think your station and mine are connected by a wire :o) You are usually the first station I hear! Your vertical is amazing".
I recently improved the radials-systems: to the 30 burried radials, I added 40 "surface mounted" temporary ones, for a total of 70 (50x10m and 20x 20m = 900m of wire!). Unfortunately, my terrain allows me the 20m-ones, in one direction, so I have now reached the maximum... Next improvement will be to add a few top-loading wires to improve the performances on 160m. The temporary "surface-mounted" additional radials. My attentive readers, may recognize them ;-)
Among my attentive readers, is my friend Dodo, F6EPY. He sent me the following pictures, of his portable vertical, made from a 18m spiderbeam mast (thanks Dodo).

Last, but not least, during the a/m exchanges with ZL1RS I was using this RX-antenna. I am now planning to put 2 of them in "end fire" configuration (using my MFJ phasing box)... More to follow...

160m: A good example of an asymmetrical path

2008-11-10T14:09:00.011+01:00

Often on the top-band, it is not easy to contact a DX station that you hear quite well. Before, accusing the DX station to be deaf, have a look at this example. I think that it is quite a good example of an asymmetrical transatlantic path.This plot shows the 160m reported levels by K1JT and mylsef using K1JT's WSPR mode. You can see that K1JT decoded me several times around his sunset, while I could not decode him. On the other hand, near my sunrise (06:28z), I could copy him better than he could. Btw, you may note that the K9AY provides a 4dB better SNR than the vertical (I was using 2 receivers), which is conform to its RDF-factor vs the vertical one (see W8JI receiving pages, k7tjr tables or ON4UN's bible). Note that we were both using 20W, which explains why the plotted levels @1W go below the WSPR decoding threshold (-30dB in 2500Hz BW)

The explanation is provided by the following plot of the noise at my location (VOACAP). You can see a 12dB variation of the noise floor, with a minimum in the middle of the day and a maximum in the middle of the night. At Joe's sunset my noise floor is very high, while it is still low at his location. At my sunrise, the noise floor is lower at my location and maximum at Joe's location. CQFD !
As pointed out by W8JI in his receiving pages, the "man made noise" is not only local noise, but also distant "man made noise" propagated through the ionosphere. In fact, based on the above plot, it seems that even at my location, the local noise is not dominant on 160m (except in the middle of the day, or in case of rain).
This is the 2MHz noise plot for my location (45.8N, 06E). A "man made" noise level" of -155/dBW/Hz @3Mhz is assumed (CCIR quiet). Of course for a higher "man-made noise" level the variation is less important (especially if the dominant source of noise is local).

VOACAP reliability, the end of myth ? part 3

2008-11-10T09:58:00.010+01:00

fig1: This plot shows the signal received by VK7KRW in Hobart, Tasmania, on 40m long path. I have also plotted DG0OPK signal (using a G5RV at 5m). In fact this plot alerted me on a problem on my vertical, as I was expecting more difference (the simulation shows -7dBi for the G5RV at 10deg -assuming it is broadside to the signal-, and about 0dBi for my vertical), Checking my antenna I discovered that one set of radials was disconnected. For this test, I was also using an auto-tuner, which is quite lossy for HighZ/50ohms impedance transformation (clearly visible on the antenna bandwidth).
Fig 2: This plot shows the VOACAP "RPWRG" output for the path F6IRF>VK7KRW. As explained in the text, all the parameters have been set to the most optimistic values... remains 40dB offset between the real world and VOACAP !

Are the WSPR reported levels accurate? I checked the reported levels with a "path simulator" (AE4JY's PathSim, a great tool !), using the same soundcard that I used for the above ploted files . Taking into account that the path simulator uses 3kHz BW for the noise and WSPR 2.5 kHz thus 0.8dB for the BW relation, I found the WSPR reported levels to be within 1dB from the Path simulator displayed SNR's. I also used several "Path algorithms" (ie CCIR good, moderate and poor) with no impact on the WSPR reported levels; so the WSPR reported levels should be considered accurate (let say +/-2dB depending on receiver and soundcard used). By the way, the only simulator path algorithms for which WSPR does not provide any decoding are the "CCIR flutter" and "High latitude disturbed"- this explains why it is so difficult in Western EU, to get a report from US-west coast (as the path goes through the aurora oval). Under the same "perturbed" conditions, JT65A works perfectly.

Where the VOACAP error may come from ?
- I think that the first source of error, especialy on low bands, is the RX antenna gain. If you reverse the TX and RX antenna you will see that the calculation provides moreless identical results in terms of SNR (+/-3db due to the noise variation along the day at the receiver location). The hams familiar with low bands DX'ing know that a receiving antenna may have an absolute negative gain, but a better receiving performance. In other words the gain of a receiving antenna is generaly meaningless in terms of SNR.The typical examples are the beverage or the K9AY loop, which have negative gain (or very negative gain for the K9AY), but provide better receiving performances than an omni antenna. A suggestion might be to use W8JI's RDF factor, rather than the absolute gain for the RX antenna. The problem is to know if the source of noise is in a different or in the same direction as the useful signal... not simple! In any case, based on W8JI table, and unless a long beverage is used, this error can't be more than 3 or 4dB compared to the isotropic antenna. Here none of the receiving stations were using a RX-antenna, therefore using the isotropic as RX-antenna can't be that wrong ! ."A contrario" using a TX-antenna on the RX side may produce exageratly optimistic results... as explained by W8JI, on HF bands, a higher antenna gain does not mean a better SNR, as the software assumes!
fig3: NEC2 simulation of VK7KRW antenna. Using an Isotropic antenna in the VOACAP model is also exageratly optimistic !

- Another potential source of error might be the 3Mhz noise level at the receiver location. Measured here on a base-loaded 18m monopole tuned at the frequency, the minimum noise level I can get (depending on the time, and the meteorogical conditions) is around -80dBm in 3000 Hz bandwidth (S7.5 according to my S-meter calibration table). This corresponds to -115dBm in 1 Hz bandwidth, thus -145dBW (the recommended average level, which is used for example in HAMCAP). I know by experience (having transported my transceiver in several other contest locations), that my location is noisy (I have 380kV power line passing some 200m from the antenna). It means that in most of the cases, for the radioamateur service, it might be more representative to use a lower noise level than the default one (-145dBW/Hz). The minimum that can be applied with some effect on the output is -160dBW (although the contextual help says: range 100-200), which represents a maximum of 15dB gained on the signal to noise ratio, not taking into account that there are also interferences (ie pactor BBS's, SSB, ...) on the bands that we are using, especialy on he 40m band... so the 15dB here should be considered as an absolute maximum on an ideal QRM-free band...Obviously not the case of the 40m band ! On the other hand, the bilateral data with ZL2TLD, shows that the reports offset, between his station and mine is just 4dB at long path and 10dB at short path (here, the band is far more noisy in the evening than it is in the morning), therefore applying -150dBW/Hz to 155dBW noise level at ZL2TLD and VK7KRW location looks appropriate as they both reported having a quiet site...
My location can't be considered as "radiolectricaly quiet" !

- VOACAP does not take into account the K or A index, but just the smoothed monthly SSN. Personnaly, I think that using the SSNe might be more representative for day to day conditions on high bands, as the SSNe which is obtained from the Ionosonders data, takes into account those variations of the K and A index. Anyway VOACAP does not accept negative SSN values and the designers insist that only the smoothed monthly SSN should be used. IMHO, everything depends on the considered path. For transequatorial pathes on 40m band such as the ones considered here, the SSN has almost no influence on the prediction (you can verify by yourself that, on this 40m path, any SSN value provides moreless the same output result). In fact, it seems that the SSN is mainly used to determine the MUF, which on low bands can't be considered as a predominant factor...
- Another critical parameter, is the "required reliability" percentage. As shown in the earlier published plots, using a too low percentage has for effect to predict earlier band opening and later band closure, than the observed one. Anything >50% seems to match quite accurately the path opening. As also shown in those plots, the "SNR" output provides absolutely identical results than the SNRxx when set to 50%. For the fig plot I used 10%... also exageratly optimistic, for a path that proved working every day over the month, with an excptionnal stability !
- The multipath tolerance, also has an impact. For conventionnal analog ham-modes, I think that this parameter should be ignored (setting multipath tolerance to 0 as for effect to disable the impact of this parameter). Of course for digital mode, it becomes more critical, but on the pathes considered here, the probabilility of multipath effect is very low (might be different on higher band, where both short and long path might be open simultaneously - ie EU to JA during EU mornings).
- The minimum angle might also be a critical factor. I have a quite bad take-off to the W-SW sector (long path) with some 8 degrees blocking due to a hill. However even 8degrees does not impact the prediction result, as the predicted radiation angle is some 10 to 12 degrees for the considered path. This is of course different on higher band, where the vertical radiation angle might be as low as 3 degrees, on a certain number of DX pathes.
- Remains the F-PROB parameters... must say that this is above my competency... I can only use the defaults. However those parameters (at least on 2 of them) seems to be linked to the E-layer effect (E and E's), which on this particular path at this time of the day, on this frequency, are unlikely to provide any improvement of the SNR, but more likely a degradation due to higher absorbtion.

The fig2 output was produced using exageratly optimistic parameters...still remains a large 40dB offset on the F>VK7 long path. How can it be explained ?

Fig4 the grey line position at the path peak. None of us are on the grey line...

- Everybody has heard about the grey-line improvement effect... If you look at the path at the observed signal peak, you'll see that none of us is on the grey line at the observed signal level peak...
- Another Hypothesis, is some "exotic" propagation mode that has not been taken into account in the model: for example and as suggested by several authors, some ducting within the ionosphere (something similar to the troposheric VHF/UHF modes, but in the F2 layer), or some other mode (ie interaction between E and F layer, or direct F2-F2 (or F2-F1 mode), avoiding the signal to be returned to earth in the middle of the path), thus reducing the path attenuation. The problem, is that "exotic" does not apply to a propagation mode which occurs every day with a remarquable stability !
- The last one is that VOACAP has never been calibrated for those "long DX" pathes, as the main objective was broadcasting at distances not exceeding 10,000 kms. As shown in my first study, I personnaly still have doubts about the proper calibration of VOACAP, even at shorter distances, but this may be the topic of another study... Anyway, and as a temporary conclusion, I think that this humble contribution shows that VOACAP predicted levels cannot be considered reliable for long DX pathes. Remains that VOACAP predicts quite accurately the best time for a given path and most probably the proper required min radiation angle, those 2 parameters being in fact the most importants for a DX-man or a contester... Anybody who is familiar with the 40m band knows that it is quite easy to work VK/ZL from EU on 40m at long path in the EU mornings, even using Low Power and a modest antenna. I personnaly had many CW QSO's with VK/ZL just using a R7 vertical and 100W. VOACAP tells you that it is not possible, unless you use "broadcast type" antennas and power... Of course VOACAP is completly wrong on such pathes, but it is the vocation and the beauty of ham radio to investigate unexplored terrains ! Just remember that the radioamateurs were the first one to explore the HF bands. At that time, all specialists were considering those frequency ranges as completly useless, so even if VOACAP tells you that a path is not possible, just try it, VOACAP can be wrong ! Patrick Destrem - F6IRF October 2008
Fig 5 Using what look "reasonnable parameters" for the path and stations setup, the offset can be as large as 73dB...

Acknowledgements: I would like to thanks, all the radioamateurs who have contributed to this article, consciently or not; between others: AE4JY, DG0OPK, G4ILO, K1JT, VE3NEA, VK7KRW, W1BW, ZL2TLD, ...

VOACAP reliability, the end of the myth ? part2

2008-10-21T08:49:00.006+02:00

Following are a few more plots concerning the F to ZL2 path. The above plot shows the signal levels reported by ZL2TLD over a longer period than the earlier published one. You can see that the delta between the lower and higher reported levels, is around 10dB, which can be explained by day to day propagation variation, but also by some punctual intereferences (we are not alone on this part of the band). The long path "average" is around -22dB for 1W TX power in a -1dBi gain antenna (simulated gain of my vertical at 10degrees). The short path average, under the same conditions, is some 2.5dB higher. Now here are the VOACAP simulations for the short and long path. This time I used method 30, CCIR monthly coefficients (and NOAA monthly SSN smoothed indexes). I used "isotropic antennas" (both antennas have negative gain at considered 10degrees angle) and switched the multipath "off". I used -150dBW/Hz noise level at 3Mhz (5dB quieter than the average recommended -145dBW), and pushed the required SNR to 12dB (-22dB observed +34dB for BW relation). The result is about the same... 50dB are missing to make the link possible...

Above is the short path... about 40dB are still missing to match the observed -20dB average level in 2500Hz, to the VOACAP simulation (forgetting that both antennas have negative gain, when compared to the isotropic used in the models.)
It is not all, but of course I kept the best for the end... stay tuned !!!

VOACAP reliability, the end of the myth ?

2008-10-17T07:55:00.011+02:00

Sorry, I have been away from the blog for quite some time... Just that I was blogging elsewhere ! Following is a series of articles recently published on the wsprnet.org site, which question the actual reliability of VOACAP ionospheric simulations. Just as a reminder WSPR is a bidirectionnal (TX/RX) digital beacon mode invented by K1JT, which provides a SNR measurement and automatically uploads it to a Worlwide database. The sensitivy is extreme (-30 dB in 2500Hz bandwidth, equivalent to +4dB in 1Hz bandwidth). Here is the first article (slightly modified).

In April 2008, I published an article on my personnal blog showing some offset between the levels reported by WSPR and the VOACAP models. This article was based on reports provided by W1BW on my 30m WSPR signal. I am now working on the data collected during the 40m daily tests with ZL2TLD. The first results are even more surprising...
Without entering now into details, I find some 50dB offset between the WSPR reports and the VOACAP models...

There are a 3 hypothesis:
1- I did a big mistake somewhere... (to get 50dB difference it has to be a very big mistake !)
2- VOACAP is not properly calibrated for >10,000kms pathes, or for vy low SSN's, such as those we are currently facing.
3- We all took for granted that VOACAP was the ultimate ionospheric prediction tool, without seeing that it could be completly "out of range" in a certain number of cases.

To convince you that there is a problem, have a look at the attached. It has been obtained using the popular VE3NEA's HAMCAP (free on his site). With this interface to VOACAP the risks of mistake are minimal (you just setup, the TX power, and the type of antennas at both sides). The solar data is obtained automaticaly through IONOPROBE (or manualy through the usual means).

- First is the setup screen (you may click to enlarge), showing that I configured Hamcap for 100W TX power (for antennas I used a 1/4GP on TX side and a dipole at 55 feet on RX side).
- Following is the chart screen, showing an expected level of -25dB, for the "long path" (had put the mouse in the middle of the yellow rectangle, on the 7Mhz line, to get the 0530z SNR displayed at the bottom)

- Finaly is a plot of the long path WSPR-reports at 1W normalised TX power (the offset between the 2 series of reports, can easily be explained by a higher noise level at my location)

Now just a few maths: - I used 100W as TX power in hamcap, thus 20dB above the 1W normalised power used for the data plot
- VOACAP or HAMCAP are using SNR's in 1Hz bandwidth; WSPR in 2500Hz bandwidth... the bandwidth relation translated in dB's is 34. Which means that you need +4dB in 1 Hz bandwidth to get WSPR to report -30dB in 2500Hz.
Here the expected level is -25dB, thus lacking some 29dB to reach the required +4dB SNR in 1Hz bandwidth.
In short VOACAP tells you that the path is impossible, lacking some 49dB of antenna or power gain... Even 55 if you consider that the average bilateral levels peak at -24dB and even more if you consider that I used a dipole at 55 feet in the model and that Glenn is using a windom at 15 feet !!!

The attached VOACAP plot, is for the Required Power and Antenna Gain, vs time. You can see that according to VOACAP 51.47dB are missing to get the required +4dB in 1Hz BW (for 33% reliablility) - moreless the same value provided by HAMCAP in the above-example.
For this one I used "method 21" (long path forced model), but the classical "Method 30" gives exactly the same value.
While the minimum RPWRG is reached at 0600z, which matches exactly the observed maximum, the "required Power and antenna gain" is completly out of range... According to this graph, I should run some 400kW to have 33% probablity to get a -25 WSPR report from ZL2TLD, while it works every day at 2 W (even at .5W) !
Serious offset isn't it ?

Now; If you believe that I did a big mistake somewhere, I invite you to access the wsprnet.org database, and work on some of the huge data available there.

More to follow...

SV*/F6IRF/M

2008-07-21T10:14:00.003+02:00

Je serais en Grèce, à partir du 24 Juillet et jusqu'au 12 Août. Au programme, tourisme, plage et radio dans le Nord: SV6, SV2, SV4, SV1, peut-être SV7 et probablement une des îles de la mer Ionienne ou de la mer Égée (SV8).
QRV mobile essentiellement sur 10m et 6m. Les fréquences de prédilection 28024, 28424 et 50224. Pour tester la propagation 10m SV>F, le mieux est d'écouter la balise SV3AQR sur 28182.6. Pour info le path était ouvert quasiment tous les jours pendant ces 2 dernières semaines.
Au plaisir d'un QSO !

SY3M - A few audio recordings

2008-06-06T13:11:00.007+02:00

80m sunday at sunrise. From Greece, end of may, the US windows on 80m is not very wide... But the 6 points QSO's are always welcome, worth making the effort ! (op Pat)

Sunday morning on 40m, just after sunrise. As usual in the WPX , 40m is the "money band" with the highest point/QSO average. Unfortunately, we missed the recording of the first hours, which provided the higher rates on this band... We could not explain the rythmic noise on the K3 recording, maybe a "knocking spirit"... (Op Nico)

Saturday morning on 10m. The 10m band provided good rates, but with a low point average despite a few DX's. (Op Pat)

The bigger 10m surprise has been a one hour opening to JA on sunday morning. We worked 20 JA's and 1 HL A selection of a few of them. Most likely multi-hop E's. BTW, the ghost is back ! (Op Pat)

20m also provided good rates despite our low gain/low height antenna, but difficult to find and keep a clear frequency. (Op Nico)

An amazing recording done on 40m a couple of hours before the contest end. (Op ?)

A vertical half-moxon for the 40m band

2008-06-04T17:36:00.011+02:00

The MMANA model: Not obvious here, but there is a 20cm gap between the 2 horizontal parts.
Following is the description of the 40m array we used at SY3M. The antenna was designed "on the spot" and constructed very quickly using 2x 10m fiber masts. It is composed of 2x inverted L's facing each other with 6m spacing between the 7.4m vertical parts and 20cm separation between the 2 ends of the horizontal parts. We used two sets of 10x10m ground mounted radials for each monopole. As we did not know the "velocity factor"of the plastic insulated electric wire, we used the same technic as we used for constructing the wire beams at CN2WW for the ARRL. Suppressing the reflector on the model gives X=0 for 7.372Mhz.
The MMANA simulation, using MININEC "average" ground.
We cut the driven element accordingly, which gave us the velocity factor of the wire (0.96). The R at X=0 was measured at 33 ohms; exactly what was predicted by the model inserting a 1 ohm resistance, simulating the ground losses at the base of the monopole. We then cut the reflector taking into account the 0.96 velocity factor. After a few minor adjustments, consisting in inserting small pieces of wire at the base of the elements, we obtained X=0 for 7.025... this was kind of useless, as the bandwidth is extremely broad, as predicted by the simulation. In fact the only major difference with the model, was that the R value, was found at 50 ohms, and not at 36 ohms as predicted by the simulation using mininec ground, but it did not worry me, as I know that Mininec is not very accurate for the R-value as this calculation is done on a "perfect ground" basis.
The MININEC simulated SWR response. The very broad bandwidth (about 300kHz at 1.5), was confirmed on the real antenna. The impedance was found very close from 50 ohms on the real antenna.
On top of this, the practical antenna was somewhat different from the model, due to the flexion of the fiber masts (we had actually 6.5m between the 2 masts bases).
First "on the air" tests were done on the Russian C-beacon (Moscow) on 7.039 a the end of the afternoon; compared to the 16m vertical, tuned on 7Mhz, the difference was constantly over 2 S-points in favor of the half-moxon (about 6dB on the pro2 S-meter). We found this difference to be quite constant for all stations in the North sector, the difference becoming minimal on the EA stations located West of us.
MININEC simulated Gain and Front to Rear ratio vs frequency.
Our 40m score during the contest and the fact that we often won the "power battle" and got first in the pile-ups, confirmed that the antenna was working fine. The simulated gain using mininec average ground and 1 ohm resistor simulating ground losses, gives 3.3dBi at X=0 and near to 20dB F/B, the gain being -0.1 dBi for the radiator alone. This value might be a bit pessismistic, as the simulated gain for the radiator alone, using NEC2 finite ground and 10x10meters radials is about 1dB higher than the model using mininec ground. Unfortunately NEC2 finite ground does not allow to specify 2 sets of ground mounted radials with different centers. Later (on the ship) we simulated a NEC2 model using a Sommefeld-norton ground and 2 sets of 4 elevated radials, which confirmed an impedance close to 50 ohms, a bandwidth matching the measured one,a gain slightly over 3dBi and a F/B ratio of 25dB.
MININEC patterns from 6.8 to 7.25 Mhz.
Of course we could have gone for a 2 vertical monopoles passive array (driven+reflector), but the horizontal pattern would have been sharper and the array more difficult to match, due to the lower radiation resistance. We liked the cardioid pattern of the half Moxon and his very broadband characteristics, making the construction somewhat uncritical.
Dimensions (for 1.6mm diameter bare copper wire with vel.coeff 1)
and Fo= 7.025
vertical parts height: 7.40m
Driven horizontal part: 2.7m
Reflector horizontal part: 3.20m
Gap between the horizontal wires: 20cm
Separation between the verticals: 6.10m

Above, the NEC2 simulations using a model with 2x4radials, over a "Sommerfeld-Norton" average ground.

SY3M in the WPX, the video

2008-06-03T14:21:00.005+02:00

The "rats terminators" in the CQ WPX. More than a "contest video"... hope you enjoy !
This video is also avalaible on dailymotion (better quality)

SY3M, the photo album

2008-05-28T20:42:00.004+02:00

You can see the SY3M expedition photo-album by following this link

SY3M 2008 WPX-CW by the "rats terminators" contest group

2008-05-28T07:42:00.022+02:00

Operators: Nico SV3SJ, Pat F6IRF
QSO details and claimed score here TRX: K3 + TT Titan, pro2 + AL1500ANT: 2el SteppIR @9m, Ground-mounted vertical Half-Moxon (40m), 16m ground mounted vertical (80/160), K9AY RX-loop and 120m beverage to JA
MSC: N1MM, Microkeyers, laptops, ICE filters, 700m of wire, 250m of coaxial, 200m of rope and a lot of enthusiasm and energy to setup/dismantle all this !!!
Under Max's hass, some of the hardware used for the operation !
My initial personnal plan was to go back to CN with some ambitions in the SOAB category, but for some obscur administrative reason the licence never arrived. On his side, Nico had already planned a trip to his home country... I could not miss such an opportunity to go back to wonderful Greece, so we quickly improvised something to be on the air; not to be competitive, but to take part, which is the most important as says the Olympic games chart! (another famous Greek/French joint venture !)Among the difficulties to setup a all-bands M/S station from scratch in a remote location, the first one was to rehabilitate a house, unnocupied by humans for some 20 years (adopted by rats and mices and invaded by wild vegetation); It took a few days to make the house usable, but we managed it... The cohabitation with the dense rats population was not always easy, but they finaly accepted to free-up some space for us (must say that we had to insist a bit, using some powerful unfair arguments... the main problem for me with the Greek rats, being that that they understand only Greek and they start working at sunset until sunrise...).Waiting for Nico to complete some "non-ham" obligations and beside some 6m and peri-contest activity (about 800 Q's as SV3/F6IRF ), I started by installing my 16m multiband portable HB vertical, tested the week before in britanny.
The 16m vertical used for 80 and 160. Alone it consummed some 300m of radials...
After a few tests on the air, I started to think about some more efficient solution for 40m, which is key band in this contest. We needed something simple, that we could setup quickly with the hardware we had (2 fiber 10m telescopic masts), so after a few simulation sessions we decided to go for a vertical "half-moxon" mainly for his broad horizontal pattern (a description will be published later here). Must say that the results overtook my expectations, the difference with the vertical being obvious right from the first listening tests. It was confirmed during the contest, as we did not get any problem to break the pile-ups and get DX stations to call us.
The vertical base; despite the poor ground quality, it worked fine...
Obviously the weak band has been 20 meters, due to the low height and limited gain of the antenna, but we could not do better for this time...10m provided some nice openings, including to JA (most probably multi-hop E's) and 15m a nice combination of E's and F2 propagation.
The driven-element of the half-moxon which gave us a strong signal on 40m. Another 200m of radials !!!
At the end we are just short of multipliers to be "almost competitive"- we had initialy planned DX-cluster through a VHF packet-link to Kalamata, but the distance and terrain profile between Kalamata and Pilos area did not allow it to work. We obviously also missed a second antenna on the high bands - but we did no expect them to be so productive and to say the truth we ended up short of time and energy (the temperature on those days did not help) ! - Anyway, in may still be a new Greek M/S record...
The SteppIR at 9m. On 20m difficult to compete with fixed stations using large antennas or stacks at a decent height.
I really enjoyed those 2 weeks in this still preserved paradisiac wild area... unfortunately not for long, as in many other places, the "beton" is about to win (a large touristic ressort is already in construction, a Motorway is scheduled and the promoters all around). A special mention to the Greek local people for their "way of life", sometime a bit annoying for a stranger, but so nice at the end !
73's from Sunny Greece - Pat
PS: More to follow here soon including a video for which I have a lot of raw material...

WSPR 80m tests from IN87

2008-05-07T21:27:00.003+02:00

The above plot shows the 80m WSPR-data collected from W1XP (FN42fo) and my portable station (IN87nn) during 4 nights, from May3 to May7 (about 250 spots). 4 to 10W were used on both sides but all plotted levels are normalized to 1W.
The general trend, over the 4 nights is a 6 to 7dB offset in favor of W1XP transmitter, with a 10dB peak around 01:30. This may indicate a higher TX antenna performance or a higher noise floor (or both) at W1XP. It is interesting to note that at W1XP sunset (when the band opens for him), he seems to hear me better. As suggested by ON4UN in "low band DXíng", the explanation may be linked to a lower noise level while the D-layer is not yet fully dissipated. This is confirmed by the below VOACAP Noise-power plot for Boston area, where we can see that on 3.5Mhz, the noise is minimal 3 hours before sunset and maximal in the middle of the night (The below graph is for a very quiet site, the variation may be partly or totaly cancelled or changed if the main source of noise is local). Those variations, although the power and antennas gain remain constant, do not mean that the propagation is not bilateral,just than the noise is not distributed equaly at both locations. The 7 dB offset trend clearly means, that my TX antenna does not work as well as W1XP's one (unless some problem on W1XP's Receiver, signal treatment, QRM,QRN, birdies, etc...). The only way to know would be to compair with a third station used as reference.

F6IRF/P IN87NN

2008-05-04T20:26:00.007+02:00

One example of last night 80m session. As usual all levels are normalized to 1W. Apparently my 80m portable antenna is working fine...

The portable antenna, just a bit shorter (16.5m) than my home one, but built on the same principle (see the best of this blog). Built with a light telesopic mast, a steppIR fiber element, and a a light fishing rod.

Just a dozen of 10m radials laying on the ground, enough to get the radiation resistance close to 28 ohms on 80m. Matching is just done by a serial coil and 28/50 ohms UNUN.

Is the propagation always bilateral ?

2008-05-02T16:36:00.004+02:00

Having done, quite a few "single band" contests along the past years, I had noticed more than once, that at band opening /closure, a few DX stations could be heard at a decent level, even at strong level, but that it was impossible to get through. Until a few days ago, my opinion was that it was because the band being wide open for them, they had stronger QRM level.
I must say that the following graph changed my opinion... at least I have a serious doubt...
Above is the plot made from WSPR 30m spots between Joe K1JT and my station during the 2 first weeks of April. As usual SNR's have been adjusted to take into account the TX-power variations (all SNR's being normalized as if both stations were using 1W).
I had noticed Joe spotting me quite frequently in the morning, while I could not hear him at all. Thought that it could be explained by a lower noise floor at his location. Plotting the above, introduced a doubt, especialy this 2h30 offset between the maximums... (the max being moreless equal). If you have an opinion about this interesting question, or if you want to repeat the same kind of plot with another pair of stations (the data is available for everybody in the wsprnet.org database) you are welcome !

Is my K9AY working as expected ?

2008-05-02T11:52:00.010+02:00

Following is another example of the interest of WSPR and the network of bidirectionnal beacons that is building up. Last night the activity focused on 80m band; a good opportunity to test the RX performance of my K9AY-loop versus my vertical. Once again I used my automatic switching system (see previous posts) to switch from the vertical to the K9 every ten minutes. I inserted a step attenuator in the TX antenna line to the RX, to balance the noise floor on both antennas (and avoid soundcard input overdriving). Following are a few results, based on limited number of spots, but which IMHO already give interesting indications (as for any statiscal method, more samples more accuracy). As for the previous plots published on the blog, all levels are normalized as if the transmitted power was always 1W - Of course it assumes that the operators are honnest, with their claimed power level, but for this particular exercise it does not really matter. The beauty of WSPR is it provides directly the SNR (Signal to Noise Ratio), which is the most interesting parameter when you want to compair receiving antennas.
First is the theoretical pattern of the K9AY, with the direction of the considered stations (I took the station that I copied more often, taking care that I had a balanced number of spots on each antenna). the pattern is for 30 degrees elevation... to be more accurate, the pattern should be considered for the circuit elevation, but this is just an indication. The important follows...

We can see on this first plot that the K9 is much better for G4MQL, while the vertical is more favorable to F1VS, especialy in the evening. By the way we can see the propagation drop at short distance during the night...

The second plot is for SV2BBO... I leave you to make your conclusions...

Finaly are the plots for several US stations, and for VE1RG and VE1VDM ( I put their spots together, as they had equal number of spots, and they are not that far away from each others).
So now, I think that we have the answer to the inital question: Is my K9AY working as expected - YES !
What is the benefit of such a receiving antenna: for my personnal case on 80m, an average 5 to 6dB if the station is in good part of the half-circle. Enough to make a QSO feasible or not ! Not too bad for such an inexpensive antenna which takes very little space ! (mine is a half-size one and only has 1 direction - the least noisy one which is North). Of course in particular DX direction, it won't compete with a long beverage, but I don't have the space for a beverage... ;-)

A multi-turns magnetic-loop for the top band.

2008-05-01T16:46:00.009+02:00

Here is a description of the magnetic-loop that I am using for the 160m band. As shown on the plots published in previous posts, this is the receiving antenna (from many I have tried) wich provides the best rejection of the white band noise generated by the 380kV power line, passing some 200m from my antennas. It is made of 6 turns of RG58 cable (only the copper shield is used) on a PVC structure. The square has 0.8m by side, so 20m of cable are required. The loop is loaded by an adjustable capacitor (required value about 65pF), the coupling to the feedline is made through a small delta loop, matched with a 1/4 balun (200 ohms port to the bottom of the delta). The magnetic loop is made of 6 turns of RG58 cable on a PVC structure. You can see the power line behind ! Best power line noise rejection is obtained with the loop a 90 degrees. The measured line noise rejection is approximately 12dB, enough to make stations to emerge... You can see the loop bandwidth on the 756 spectrum display. The horizontal scale is 20kHz/div while the horizontal scale is 10dB/div. Very narrow ! For my noisy location, using the 20dB transceiver preamp, provides enough level to get the noise floor to S4 with a 2.4kHz filter, so no additional preamp is required.The MMANA-model, seems to match quite closely, the real antenna. The measured SWR is about 1.5 at resonnance, good enough for a receiving antenna... On the model the capacitor is at the top of the loop (just beacause it was easier to draw!). On the real one the capacitor is in the small electrical box at the bottom of the loop (it does not change anything !).The simulated pattern. The horizontal pattern is for the loop at low height above an average soil for 5 degrees elevation. At higher elevations, the pattern becomes an oval with low directivity, so the directivity is only useful to reject punctual sources of noise arriving at low angles, or local stations on groundwave(front to side rejection is about 30dB on the horizon). The difference between the theoretical rejection and the measured one can be explained by the fact that my noise source is not punctual...

WSPR - 160m spots analysis, or how to evaluate a station performance.

2008-04-30T19:11:00.013+02:00

For a contester it is always interesting to know how good is the site he is using, what kind of handicap or bonus he has vs a direct competitor, or what is the real impact of an antenna improvement (ie adding more radials on a vertical). Everybody knows how difficult it is to base and antenna evaluation on a few subjective S-meter reports, affected by QSB. Providing a uniform and objective reporting system (Signal to Noise Ratio), WSPR is the ideal tool, capable of providing near to the dB accuracy when enough spots are averaged. Furthermore it allows to evaluate antenna and site, accross a full window from band opening to band closure, this function of the direction and distance.Following are a few examples. Above is the plot of the spots reported by DF1VB on 160m for F1VS and F6IRF stations. As usual all reports have been adjusted taking into account the TX-power (all reports are matched as if the TX was always 1W). Of course the distance being shorter for my station(896 vs 631 kms), it is quite normal to see such a difference. GI8HXY having provided a significative number of spots for F1VS and my station during two 160m recent nights, I repeated the experience. This time the distance difference is not that important, and in favour of F1VS, but the signal difference is slightly higher in my favour. This may be due to my house obstruction in DF1VB direction, while the path to GI8HXY is perfectly clear with just a 3 degrees horizon blocking due to the mountains (which has no effect on such a path on 160m). Of course there are many more parameters which may explain this offset (I don't even know what kind of antenna F1VS is using...)Looking at VE1VDM reports, the difference is this time minimal over time, but we see clearly the effect of the later sunrise at F1VS location. It would have been interesting to see earlier reports, but I was running too low power until 2:00 to get my signal decoded on VE1VDM side, and unfortunately Vern was not QRV last night.Back to GI8HXY reports, I plotted the most spotted 4 stations (data only for last night). On the above plots the SNR's are just corrected for power levels. Despite different data time-range, the difference between F1VS and my reports is still the same (about 6dB). OH3XR stoppped transmitting around 3:30, which explains the abrupt and early signal drop.On the above plot I have tried to correct the distance effect. For this I used VOACAP path-loss model as a function of the distance (the propagation mode being identical for the 4 stations: 1F2) and deducted a correction factor proportionnal to the distance from Transmitter to Receiver. It is amazing to see the performance of OH3XR station vs all others (to be honnest I did not remember who OH3XR was, when I did that... I just selected the 4 more spotted stations, and Marko was transmitting 500mW, so is signal level did not alert me before I plotted the above !).
I just looked at Google, and quickly found that OH3XR aka OH9XX is a famous topbander and contester and owner of an exceptionnal contest site. I have no idea what antenna Marko was using last night, but it is interesting, isn't it ?

WSPR: Evaluation of two160m RX-antennas using WSPR reports

2008-04-30T17:37:00.012+02:00

The following examples focus on the 160m band, where the WSPR activity is increasing. Last night more than 30 stations were active on the band, which was in excellent shape, with very low level of statics. The EU map show the active stations between 21 and 22z, while the map covering EU and USA show the active stations between 2:30 and 3:30Z. Using the automatic antenna switching described in the previous posts, I took this opportunity to try to evaluate the performance of my two RX antennas. Although the number of spots considered is somewhat limited it already gives interesting indications. For the following plots, all reports have been normalized to 1W (deducting/adding the corresponding dB's when more or less power was used).The above graph shows the performance of my RX magnetic loop (in red) vs my K9AY (in blue) for a 850 kms circuit. Both antennas are pointing north (direction where my power line noise is minimal). Both antennas have a broad pattern, with a min E/W for the loop, and a min to South for the K9AY. For this direction/distance the magnetic loop is about 2dB better than the K9AY.As shown on the above, increasing the distance, tends to reduce the difference (the above plot is for a 2000 kms path) . Due to the limited number of spots from USA (especially on the loop), the plot would be meaningless, but it seems that the K9AY is working better at a longer distance, as more than 2/3 of the US spots were obtained using the K9AY. Will come back, on this when enough data is available. The above graph, shows the directivity of the loop, as F1VS is moreless located on the deep of the loop pattern and at a distance of 450kms. I was wondering if the directivity of the loop was still good for signals arriving quite high above the horizon... the answer is obviouly yes! (the K9AY has about 3dB front to side), in this direction the K9AY is obviously better (btw I have no idea how to explain the sinusoidal shape of the loop curve... but considering the limited number of spots, it may just be a random effect...). Those results are obviously only valid for my location, where my main problem is to eliminate the noise generated by the very High Voltage power line... The moon before moonset. The line is running East-West and located in my South. On 160m, the minimum noise is obtained with the magnetic-loop perpendicular to the power line (N/S). The noise floor increases by some 10dB when the loop is oriented E/W.

A statiscal method to evaluate TX antenna performance using WSPR - more...

2008-04-25T10:46:00.006+02:00

The following graphs are based on a significative number of spots and show, what can be expected from the method described in the previous post. All have been done on 30m, as for the moment it is the band where the WSPR activity is maximum. The above graph, shows all the spots (about 2500) collected from 23 april 10:00 to 25 april 5:00 for the 2 antennas under test (5/8 vertical and dipole at 10m). Such a graph may look useless but similar plotting may be of interest for contesters, who want to reach a maximum of stations in all directions at all distances in a limited period of time. The slight superiority of the vertical can be easily explained by the fact that it is omnidirectionnal, thus allows a stronger signal in all directions, even at short distances. This would look probably different on lower bands, where high angle signals are more dominant for non DX stations. It would also probably look different with a 1/2 wave vertical which has a sharper pattern in the vertical plane and unlike the 5/8 no secondary lobe at high angle (see the article describing my vertical ).
For the above graph, I only used the data from DX stations (>5000kms - about 650 spots). It should be noted that the orientation of the dipole (310/130) is near to optimum for a huge majority of the spotters. It just confirms antenna simulation and what all experienced DX'ers and contesters know: For DX, a well designed verticaly polarized antenna is better than a horizontaly polarized antenna, if below 0.5wl AGL.
By the way an interesting phenomena can be observed on day 2 between 14 and 20z, when the dipole seem to exhibit slightly better performance than the vertical. It could be explained, by some higher angle mode of propagation (ie E's+F) during this particular period of time... but of course this is just an hypothesis...

A statiscal method to evaluate TX antenna performance using WSPR

2008-04-24T14:18:00.011+02:00

Failing to find a proper calibration for VOACAP to use it as reliable reference to evaluate antenna or site performance (*), I decided to try something else. The method I imagined consists in switching 2 antennas every 10 minutes, 1 second before minutes 00, 10, 20, 30, 40 and 50. Selecting a 33% TX'ing rate, in WSPR you have the guarantee to have a minimum of 1 transmission per 10 minute period (most of the time 2). Swiching is done using a little software available for free on the web and a simple interface to the LPT-port using a NPN transistor to drive a coaxial relay (similar to the popular CW interface used for K1EA's contest sofware "CT").
Following are a few examples, based on limited number of 30m spots, which however seem to validate the method. The antennas used are 1) a 5/8 ground-mounted full size vertical with about 30 burried radials with a simulated gain of 0.5dBi @16 degrees 2) An inverted V dipole, with appex at 10m oriented for AZ 130/310, with gain of approx 5 dBi @50degrees.
The first graph show the spots received by VK6DI on April 23. The distance is 14000 kms, the azimut from here, is about 100degrees (so about 30 degrees from the dipole main lobe). For this circuit, and at the time of the spots VOACAP indicates a vertical angle between 3 and 10 degrees (function of the time). All the spots have been corrected, to show a normalized TX-power of 1W (I deducted the corresponding 6dB's, when 4W was used). 4 spots received by VK6DI between 2140 and 00:48 were removed, as they were received only when I was TX'ing on the vertical (leaving those spots would have biaised the comparison). The superiority of the vertical is quite obvious, and peaks at 6dB just before 20z, with an average of 4dB across the window. This is quite normal, considering the gain of the dipole at angles below 10 degrees.
The second plot is from the spots received by K1JT. The distance is 6300 kms and the azimut from here is 296 degrees. VOACAP indicates a radiation angle around 10 degrees for the considered window. The difference peaks to 7dB in favor of the vertical, with an average 3dB accross the window.The 3rd plot is based OY3JE's spots. Distance is 2000kms and the AZ 340 degrees. Here the average received signal is about the same on the 2 TX antennas, but with higher peaks on the dipole.
Reducing further the distance gives a slight advantage to the dipole. Above are GM3AKF spots, at a distance of 1400 Kms and AZ of 338 degrees.
Finaly are the spots received by EA1FAQ at a distance of 1000kms and a bearing of 245 degrees. Here the vertical takes again the advantage, likely due to the directivity of the dipole.
As mentionned earlier, the above plots are based on a limited number of spots, the method being statiscal, more spots, more accurate results... The results may also be biased by the interaction of the 2 antennas only located 15meters away. Nevertheless, the results seem quite coherent with the antenna simulation, and show that WSPR and the network of stations that is growing every day is a fantastic tool, not only for propagation evaluation, but also for antenna and site evaluation (ie using 2 stations a few kms away from each others using the same antenna). The same method could also be used to evaluate RX antenna perfomance.
(*) important differences can be seen function of the selected circuit, so evaluating an antenna or a site with sufficient accuracy, even over a period of 3 weeks was a kind of utopy...

VOACAP vs WSPR reports - part2

2008-04-21T17:06:00.007+02:00

My previous post on the topic concluded by "I leave you judge...". In fact, there was a trap: VOACAP provides SNR in 1Hz bandwidth, while WSPR provides SNR in 2500Hz bandwidth, thus a difference of 10Log2500=34dB. Quite a difference ! Following are a few more plots, in order to try determining the correct "VOACAP" calibration for WSPR. For this purpose I have used the data collected on my 30m beacon, by W1BW (near to 400 spots). All reports have been normalized to 1W ERP (I used up to 100W at band closure / opening), which explains why a few reports are below -30dB. The first plot shows, on top all the spots collected by W1BW between 1st and 20 April (the dark blue dots). The light blue curve is a simple average on 4 spots and the blue curve the polynomial order 6 function. The other curves represent the VOACAP output for the parameter SNRxx (SNR at required reliability), adjusted for 2500Hz BW, for a circuit reliability of 90%, 50% and 10%. Other parameters: Power 1W, Isotropic Antennas, min angle 3deg, Ant gain 0dBi (both TX/RX assuming omni antennas are used at each end) , Noise -152dBW (CCIR quiet) , Method 30, Absorption "Normal", Coefficients CCIR (monthly) and SSN =15 (value suggested by G4ILO's VOAprop). The "required SNR" was set to 4dB (-30dB min required signal for WSPR to decode, plus 34dB for the bandwidth relation) but this parameter has no impact on the SNRxx output, and the Fprob. parameters were set to default. Last, but not least, the values near the edge (band opening/closure) and during the period 13 to 16Z should considered with care due to the limited number of spots available. Observations: 1) the SNR and SNRxx @50% provide identical results.2)Setting the required reliability to 10% generated earlier predicted band opening and a later band closure. 3) there is a litle time offset between the observed peaks and the predicted peaks which may be explained by the fact that VOACAP provides the value for the 9th hour, which is in fact 9z to 10z.
This has been corrected on the above plot, which shows basicaly the same things, but where all spots collected in the 9th hour were averaged at 9:00z. This time the required reliability for VOACAP was set to 5%, 10%, 25%, 50% and 75%. We can see the impact of the required reliability parameter: Reducing the xx below 20% has for consequence to predict an earlier band opening a later band closure and a higher level. In fact 50%or higher seems to provide more matching results (except in terms of level, but I'll come back on this). I also wanted to see the impact of the other parameters. First the coefficients URSI88 (daily) vs CCIR (monthly), then the absorption model (IONCAP vs Normal). as you can see, those parameters have little impact on this particular path and none on the maximum levels. I also tried the 3 different methods available: method 20 (complete System performance) method 22 (forced short path model) and method 30 (short long smoothing), but on this particular circuit, the 3 methods provided absolutely identical results.
Finaly I made the SSN to vary from 15 (suggested G4ILO's VOAprop value) to 10 (predicted monthly smoothed SSN) down to 4 (VE3NEA's Hamcap suggested value, from the latest table available on his site). At this stage we can see that, using the recommended / defaults values (method 30, absorption Normal, CCIR monthly coefficients) and a SSN=4 for the SNR parameter output, seems to provide the best match in terms of band opening/closure with the observed values. Remain the 16~20dB difference observed near the 2 maximums... Is VOACAP prediction too conservative, is noise level lower than estimated at W1BW location, does he have some RX antenna gain, is the WSPR reported level too optimistic? Might be a combination of all these factors, or did I do a big mistake somewhere... more to follow and of course comments and suggestions are welcome !

VOACAP vs WSPR-reports

2008-04-17T17:57:00.005+02:00

F6IRF à VE1VDM sur 30m: En couleur, la courbe de tendance obtenue en utilisant VOACAP. A l' intérieur, la courbe obtenue d'après les relevés réels de ma balise WSPR reportés par VE1VDM (les points bleus) pendant la première quinzaine d'avril, tous les reports étant normalisés pour 1W (en ajoutant ou soustrayant les dB's correspondants quand j'avais utilisé une puissance differente ). Ci dessous les paramètre utilisés pour le modèle. VOACAP a la réputation d'être le modèle de propagation ionosphérique le plus fiable disponible à ce jour... je vous laisse juge...
F6IRF to VE1VDM: In colors, the plot generated by VOACAP. Inside, the plot obtained from the WSPR real reports during the first 2 weeks of April (the blue dots; all have been normalized to 1W, adding or substracting the dB's difference to the reports, when a different power level had been used). Below are the parameters used for the modelization. VOACAP has the solid reputation of being the most accurate ionospheric model available today... I leave you judge...

WSPR - quelques essais de plus...

2008-04-16T10:29:00.013+02:00

Voila le CR de 2 essais réalisés ces dernières 12 heures, et qui donnent une idée plus précise de ce que l'on peut ésperer de WSPR. Traverser l'Atlantique avec 4 mW sur 20m, oui c'est possible! Il en faut un peu plus sur 160, mais ça marche aussi !!!
Ci-dessus - cliquez pour agrandir - le relevé des spots reportés hier soir sur 20m en réduisant la puissance de 100mW jusqu'à 4mW.
Ci-dessous le setup utilisé pour contrôler la puissance délivrée à l'antenne (steppIR 2 elts @12m - Gain simulé 10dBi): le wattmètre (Daiwa CN801) est branché à l'envers pour béneficier de l'échelle la plus dilatée. L'émetteur est réglé pour 200mW , reste ensuite à insérer l'atténuation nécéssaire, jusqu'à 17dB hier soir (23dBm-17dB=6dBm soit 4mW !).
Ci-dessous résultats des relevés reportés par VE1VDM sur 160m cette nuit. La puissance était de 10W et l'antenne ma verticale 1/8 chargée à la base (Gain simulé -3dBi). Vern utilisait quant à lui un long fil de 400m, orienté E/W. Entre le coucher de soleil chez VE1VDM, et le lever de soleil, chez moi, l écart maximum du SNR n'est que de +/- 4dB par rapport à la valeur moyenne et pas une transmission n á été manquée. Après, un peak, la liaison s'est interrompue brutalement peu après le lever du soleil, et même un passage à 100W n'a pas permis de la rétablir.

A l 'écoute des rumeurs...

2008-04-15T11:29:00.010+02:00

On voit ici en dessus du signal WSPR de OZ1PIF sur 30m, un signal PSK31. A droite mon émission, centrée à 1510Hz (Spectrum-Lab software)

Pour une fois il est intéressant d'écouter les rumeurs ! Non, pas celles concernant les derniers avatars de la vie personnelle de notre président, mais les chuchotements dûs au dernier soft de l'illustre Prix Nobel K1JT, WSPR (prononcez "whisper"et traduisez "Weak Signal Propagation Reporter"). Pour plus de détails le mieux est d'aller sur le site de Joe en suivant ce lien. Vous pourrez y trouver une présentation du programme ainsi que le lien pour charger la version expérimentale la plus aboutie à ce jour.
Comme l'indique l'acronyme, il ne s'agit pas d'un soft pour faire des QSO's, mais d'un soft pour tester les conditions d'une bande, des modes de propagation exotiques, une liaison particulière, voire d'évaluer les performances d'une nouvelle antenne son rapport A/R ou tout ce que vous pourrez imaginer comme application possible...
Le programme de K1JT - on peut voir sur le spectrogramme le signal recu de OY3JE à 10.194. le méssage transmis par ce dernier, inclue son locator (IP62) la puissance en dBm (30dBm soit 1 W) et le décodeur indique un SNR moyen de -24 dB dans une bande passante de 2.5kHz. On voit avec speclab (ci dessous), que ce signal serait juste suffisant pour être décodable en QRSS à 3s par point. On voit d'ailleurs un signal QRSS (FSS ?) entre les signaux de OZ1PIF et de G0HNW

Le signal géneré par WSPR est extrêmement étroit (6.5 Hz de bande passante), la bande passante monitorée étant de 200Hz centrée à une fréquence audio de 1500Hz (avec un 756 pro, pro 2 ou 3, le mode USB-D et le filtre de 250Hz sont idéaux). Outre le TRX vous aurez besoin du même "setup" que pour le PSK31, à savoir un PC muni d'une carte son et une interface audio. (personellement j'utilise mon MK2R+ avec sa carte son USB intégrée), et comme pour le JT65 du même auteur, d' une bonne synchronisation de l 'heure de votre PC (temps internet, GPS, DCF77 ou autre).
Typiquement chaque station du Net, transmets pendant X périodes de 2mn, commencant à une minute paire ( 00-02-04,... X dépendant du T/R cycle sélectionné) et écoute le reste du temps. Si vous sélectionnez un T/R cycle de 20% vous allez transmettre pendant 6 des 30 périodes constituant l 'heure et écouter pendant les 24 autres, le choix des périodes d'émission étant "randomisée" afin que 2 stations données ne transmettent pas systématiquement sur la même période. De cette façon, même 2 stations ayant choisi la même fréquence à l'intérieur de la bande de 200Hz, ont toutes les chances de ne pas se gêner systématiquement pendant leur période démission, et chaque station du net a de fortes probabilités d'entendre toutes les autres.
Mais vous me direz, rien la de très nouveau... en effet j'avais moi-même mentionné ici le réseau propnet (suivre ce lien). La grosse différence, par rapport à ce réseau utilisant le mode PSK31, réside dans le niveau de performance obtenu grace au type de modulation utilisée, qui permets de décoder un signal jusqu`à un rapport Signal/Bruit de -30dB dans une bande passante de 2.5kHz soit presque 20dB de mieux que pour le PSK, et 16 bons dB's en dessous du plus petit signal CW décodable par l'oreille humaine, ce qui situe ce mode légèrement devant ce qu'il est possible d'obtenir avec les modes visuels tels que le QRSS à 3s/point qui étaient utilisés jusqu'à ce jour sur les "Grandes Ondes" (par ex. la bande 137KHz) pour repousser les limites du bruit.
Exemple de carte visualisable sur le site wspr.org Ci dessous, le site dispose aussi d'une base donnée munie de filtres. On peut y voir mon activité récente sur 80m -cliquez pour agrandir - (5000kms avec 100mW, et il y avait encore plus de 10dB de marge !)

Enfin pour supporter le tout, un site internet permets de reporter les balises entendues (cela se fait automatiquement depuis WSPR depuis la version 0.6), et de visualiser tous les endroits de la planète ou votre propre signal a été entendu. A titre indicatif c'est sur la bande 30m que l'activité "naissante"est la plus soutenue et sur cette bande, une verticale et 1W sont largement suffisants pour se faire entendre aux antipodes tant au long-path le matin, qu'au short path le soir...
D'ores et déjà ce mode offre un large éventail d'explorations passionnantes... et nous n'en sommes qu'au début... (à suivre...).

4U1ITU - RUSSIAN DX 2008 - the video

2008-03-20T00:06:00.008+01:00

The video may also be seen in slightly better quality from "you tube" by following this link.
If you have a broadband access, you may also download the video in much better quality (640x480, stereo), by following this link (about 50Mb).
You may also embed the video on your site or blog by copying the "embed" script on the "youtube" a/m page. 73's Pat

4U1ITU - RUSSIAN DX 2008 - a quick analysis...

2008-03-18T09:30:00.008+01:00

As mentionned earlier, knowing the station, I did not expect to be really competitive, so I am not disapointed. However it is always interesting to look at what could be improved...
Despite higher number of QSO's, we are not competitive... too few multipliers, worst pt/qso average. Having an attractive callsign does not fully compensate for station performance !
DR0W vs 4U1ITU: the main problem is the low number of multipliers on all bands...
Our low percentage of SSB QSO's did not help either !Our points rate-sheet by band and by mode: More SSB would have helped increasing the average Point/QSO... but except in rare occasions on 40 and 20, we did not manage to keep a decent SSB-run going... Again an attractive callsign does not fully compensate station performance, especialy when the condx are very poor... fortunately condx can only improve...

4U1ITU - RUSSIAN DX 2008 - soon here...

2008-03-18T08:23:00.003+01:00

Russian DX-Contest: A short CR is visible here. Pics, graphical stats and video, soon on this blog !

TM9R, ARRL DX CW - The video

2008-02-20T12:55:00.007+01:00

The 2007-CN2WW team (SV3SJ/F6IFY/F6IRF) is on the road again for the ARRL-DX CW contest. This time we responded to F5FLN, F6IRA and the F6KNB team invitation to use their contest site in South-West France. It did not work as well as we expected, but still it was an enjoyable weekend.If you have problems viewing the video from here, you may also try on "youtube" by following this link.

A 80m "end loaded" dipole

2008-02-04T11:20:00.000+01:00

Voici une petite combine, qui interessera ceux qui comme moi ne peuvent pas déployer un dipôle 80m "full size". Le dipôle est réalisé à partir de 2 fois 17m de paire téléphonique torsadée (2x 0.5mm de diamètre). Les derniers 3.5m de la paire sont écartés pour former une patte d'oie. Le centre du dipôle étant situé à 10m, et les extrémités à 1 m, l'encombrement nécéssaire au sol est inférieur à 27m (contre environ 36m pour un dipôle full-size) .
Avant détricotage de la paire le dipôle résonne sur 4.1Mhz; après détricotage des deux parties terminales, on arrive, en les écartant plus ou moins, à régler l'accord entre 3.5 et 3.8Mhz. La bande passante mesurée est en conformité avec la simulation NEC2, soit environ 150kHz à 2 de ROS. Malgré la finesse du fil utilisé, le rendement est de l'ordre de 93% soit environ -0.3dB par rapport à conducteur parfait, l'éssentiel des pertes étant liées à la proximité du sol (-4.5dB par rapport au même dipôle à 20m). Le diagramme est bien sûr "NVIS" avec un gain zénithal de 1.35dBi soit environ 0.8dB en dessous d'un dipole "full size"en fil de 2mm de diamètre à la même hauteur. Moralité: il ne faut exagérer ni les pertes liées au raccourcissement, ni au diamètre du fil...
Note: en plaçant les extrémités à 90 degrés, on peut réduire l'encombrement au sol à moins de 22.5m, au prix d'un petit sacrifice de gain supplémentaire (voir illustrations en bas du page). This is a tip, for those, who like me don't have enough space to deploy a full size 80m dipole. This dipole is made from 2x17m of a twisted telephone pair (2x 0.5mm diameter). The dipole appex is 10m AGL while the ends are at 1m. The last 3.5m of each leg are untwisted and spaced to form a Y. The ground span required is less than 27m (against 36m for a full size dipole). Before untwisting the pair, the dipole resonnates on 4.1 Mhz, after untwisting the ends any center frequency from 3.5 to 3.8 Mhz can be obtain by changing the end spacing. The measured SWR closely matches the NEC simulated ones. Despite the thin wire used , the efficiency is around 93% which is only 0.3dB below a perfect conductor, most of losses being due to the low height (-4.5dB compared to the same dipole at 20m). The pattern is NVIS, with a vertical gain off 1.35dBi, just 0.8dB below a full size dipole made of 2mm diameter wire at the same height. Conclusion: losses due to dipole shortening and wire diameter should not be over estimated ! Note: by placing the ends at 90 degrees it is possible to further reduce the dipole span to less than 24 meters on the ground, at the cost of further gain reduction. Une version encore plus compacte (2x 11.21m au sol). Le dipôle mesure 2x14.13m et les fils formant les capacités teminales 4x3m. la bande passante est d'environ 150kHz à 2 de ROS et le gain vertical de l 'ordre de 0dBi. Ce dipôle compact en "fil fin" ne rends que 2dB à un dipôle "full size" en fil de 2mm de diamètre à même hauteur. A further compacted version (2x11.21m on the ground). The dipole is 2x 14.13m and the 4 wires making the end loading are 3m each. The bandwidth is still around 150kHz at SWR 2:1 and the vertical gain about 0dBi. This compact "thin wire"dipole is only 2dB below a full size dipole made of 2mm diameter wire, at the same height.

A low cost preamplifier for the Cizirf special

2008-02-03T10:38:00.000+01:00

Voici un préampli pour la Cizirf-speciale réalisé uniquement avec des fonds de tiroir ! Avec les valeurs du schéma, le courant emetteur est d'environ 35mA, ce qui mets le 2N2907 à la limite de la dissipation admissible (ce pourquoi il est muni d'un radiateur). Si on a ça sous la main on peut également utiliser un 2N2905 capable de dissiper un peu plus. Le réglage du gain de 20 à 26dB a été prévu pour une utilisation avec la Cizirf-spéciale. L'alimentation est faite au travers du cable coaxial, le préampli étant destiné a être placé au plus près de l'antenne. Pour une meilleure protection de l'entrée, il est possible de monter un petit relais court-circuitant l'entrée quand le preamp n'est pas alimenté. IP et NF seront mesurés ultérieurement, mais même connecté à l'antenne d'émission, et sans filtre de bande, le preamp ne crée pas de produits de mélange décelables. Ça doit présenter aucun problème sur une antenne de réception avec un gain très faible (comme le dipôle version 2 ci-dessous). Le proto du préampli: la capa volante permets le découplage de la résistance d'émetteur - sans découplage le gain est d'environ 20dB; il monte à 26dB avec. The preamp protype. The flying capacitor is for the decoupling of the Emitter resistor: Without capacitor the gain is abt 20dB and it is about 26dB with the capacitor on.
This is a preamp for the "cizirf-special" made only from junk-box components. With the indicated values, the emitter current should be around 35mA, which places the 2N2907 near the maximum admissible power dissipation (why it is equipped with a radiator). You may replace the 2N2907 by a 2N2905, which has a higher power dissipation. The gain adjustment from 20 to 26 dB has been made with the "Cizirf special" in mind. The preamp is supplied through the coax cable, for remote installation near the RX antenna. For a better input protection, it is possible to install a small relay short-circuiting the input when the preamp is not powered. IP and NF will be measured ASAP, but even connected to the transmit antenna, without band filtering, the preamp does not produce any detectable intermod products. It should be no problem on a low-gain RX antenna (like the version 2 dipole below).

A new dipole for the "Cizirf-special"

2008-02-03T09:14:00.000+01:00

Voici un nouveau dipôle pour la Cizirf-spéciale, pour ceux dont la place limitée ne permettrait pas de déployer 2x15m de fil. Outre l'encombrement, il a l'avantage de présenter une adaptation sensiblement meilleure que la version 1 et d'être utilisable sur une large bande de fréquence. Il a l 'inconvénient de présenter un gain moins important, ce qui necessitera l'emploi d'un préamplificateur, au moins pour les bandes 160 et 80m. J'ai construit le mien avec une paire téléphonique torsadée (2x0.5mm) , mais moyennant quelques adaptations mineures on doit pouvoir utiliser du twin lead, ou même du "scindex". Le transfo est réalisé sur les mêmes ferrites que le balun de la version 1 avec 4x2 tours (est. AL=1000). Avec l'antenne a 4m du sol le SWR et gain mesurés sont conformes aux valeurs simulées avec NEC2.Gain en espace libre. le gain à faible hauteur (3~4m) est d'environ 10dB inférieur. Free space gain- The actual gain with the dipole at 3~4m AGL is some 10dB lower.

This is a new dipole for the "cizirf-special". On top of a reduced spacing, it exhibits a better match and a broader bandwidth. The drawback is a lower gain, which will probably require the use of a preamplifier at least for the 160 and 80m bands. I built mine with a telephonic twisted pair, but 300ohms TV-twin lead or even a simple domestic electrical pair should also work. The 1/16 transformer is built on the same ferrite beads (est. AL=1000) as version 1 with 4x2 turns. With the antenna at 4m AGL, the match and gain are identical to the NEC2 simulated values.

erratum

2008-01-29T11:13:00.000+01:00

Juste pour signaler une erreur dans la liste des opérateurs sur le post 3830. Seb F8CMF était bien chez lui en "single op" et PM HB9DTM avec l équipe F8KCF. Cette liste était celle du CQWW RTTY 2006 .Mes excuses aux intéressés ! La liste correcte des opérateurs; F5VIH/SV3SJ, F6IFY, F6IRF
Just to spot a mistake in the operators list on the 3830 post. Seb F8CMF took part from home as single-op, and PM alias HB9DTM with the F8KCF team. This op list was for the CQWW RTTY 2006 . Sorry for this ! Correct op-list: F5VIH/SV3SJ, F6IFY, F6IRF

The "Cizirf-special" first real test

2008-01-29T08:52:00.000+01:00

The "Cizirf special" at F6KAR for the HF-CW leg of the French Championship
This weekend took place the CW-leg of the "French Championship". This was a good opportunity to test the "Cizirf-special" in real contest conditions from the CERN radio-club F6KAR. The antenna was installed 5m AGL, on 2 fiber poles, as far as possible from the transmitting antennas and using the MFJ-1025 as phasing unit. The phasing box was controlled by a foot-switch, allowing to change instantly from a NVIS "omni" pattern (single dipole) to a predifined directionnal pattern. Although the antenna will probably be more useful during the SSB-leg, we all appreciated to be able to pull out weak stations from the saturated 80 and 40m bands. To learn more about this antenna, you may browse the 2008/01 archives: several videos, and many audio recordings are used to illustrate the topic. The full description in english is available by following this link.

test de la "Cizirf-spéciale" à F6KAR

2008-01-28T16:10:00.000+01:00

La "Cizirf spéciale" à F6KAR pour la coupe du REF-CW.

Ce weekend de "Coupe du REF CW" a été l'occasion de tester la "Cizirf-spéciale" en conditions réelles de contest. Les 2 dipôles amortis ont étés installés E/W à 5m du sol sur des mats en fibre de verre, en contrebas des antennes d'émission, 2 fois 50m de RG213 servant à connecter les dipôles à la boite MFJ-1025. Une pédale permettait à l'opérateur de "bypasser" la boite, et d'obtenir ainsi très rapidement un diagramme NVIS "omni" (un seul des 2 dipôles étant alors connecté).

Hervé, "l'écureuil de KAR" hissant la réhausse pour le dipôle 80m au sommet du pylône.

La boite ne disposant pas de préréglages, j'avais pris la précaution de noter quelques réglages standard avant le début du contest, principalement et pour chaque bande un réglage éliminant les stations venant de l'Est et un éliminant les stations F. C'est Nico qui a le mieux résumé les choses: "C'est le premier contest depuis le club, ou j'ai l'impréssion de faire de la CW sur VHF, tout en étant sur 80m". De fait, depuis notre position près de la frontière Suisse, et aussi curieux que cela puisse paraitre, c'est le réglage "East only" qui s'est avéré le plus utile, permettant l'élimination des "keys clicks"et autres QRM's dus aux stations proches en fréquence, une petite action du pied permettant de choisir entre les stations F et les stations DX. Le petit extrait du log donne une idée du bénéfice qu'on peut tirer d'un tel dispositif....
Bon tout ça m'ayant donné quelques idées de perfectionnement du système, restez connectés sur le blog... ça va continuer à chauffer !

Extrait du log. On peut voir au milieu des stations F et Europe: N7... "au long path" et BD3... Qui a dit que la Cizirf-spéciale n était pas une antenne DX ? Ah oui c'est moi ! De fait elle ne l'est pas, mais elle est cependant diablement efficace, quand il s'agit de sortir une petite station du QRM ambiant...

Cizirf special, combiner and phasing system

2008-01-23T10:18:00.000+01:00

Voici un schéma mis au propre du phasing system version "rustique"(sans électronique) et du "combiner" (derivé du BB2) . Cliquez sur l'image pour l'agrandir. Si l'on taille les lignes pour 80m, il sera également utilisable sur 40, mais avec un pas de 45 degrés.
This a clean diagram of the rustic phasing system (no electronics !) and the combiner (derived form the BB2)'. Click on the image to enlarge it. If you cut the lines for 80m band, it will also work on 40m, but the step will be only 45 degree.

Ci-contre une réalisation vite faite du transfo du combiner utilisant 2 tubes ferrite à fort indice AL (indice AL estimé1000 en uH/100 tours). Le secondaire (côté récepteur) comporte 3 tours et le primaire (côté antenne comporte 2 tours bifilaires). Le point milieu du primaire est chargé sur une résistance de 25 ohms. Celui la ne monte en fréquence, la ferrite ayant un indice AL trop élevé, mais il fonctionne parfaitement sur 160 et 80. En utilisant une ferrite d'indice AL plus faible, il faudra probablement augmenter le nombre de tours, l'éssentiel étant de maintenir le rapport de 2/3 entre un demi primaire et le secondaire.
This picture shows a quickly made transformer for the combiner. This is made on 2 high AL ferrite beads (est. AL 1000 in uH per 100 turns). The secondary (on the RX side) has 3 turns, while the primary is made of two bifilar turns. This one works perfectly on 80 and 160 and shows about SWR 1.3:1 on 40. To be able to use it higher in frequency a lower AL-ferrite would be required. The optimum number of turns can be determined experimentaly, just the 2/3 ratio between a half primary and the secondary needs to be maintained.J'en profite pour "spoter" la réalisation de boite de commutation, publiée sur le site de F6ETI, qui vous rendra les plus grands services si vous n'avez pas d'entrée "RX-antenna" sur votre transceiver.
I take this opportunity to spot the description of a switching box for RX antennas, published on F6ETI website. This will be very useful if your transceiver is not equiped with a RX-antenna input.

The "Cizirf special" as a QRN-killer

2008-01-21T10:07:00.000+01:00

Ma source de bruit locale / My local source of QRN !
Un autre bénéfice de la "Cizirf spéciale" est sa propriété d'élimination de QRN locaux. Ce clip audio, enregistré ce matin sur 40m, donne un exemple sur un QSO entre un station ZL et une station DL. Bien que cette antenne n'ai pas été concue pour le DX, elle peut néanmoins s'avérer utile si vous êtes affecté par une source de bruit locale. L'enregistrement a été obtenu en utilisant la boite MFJ-1025 et une pédale connectée à son entrée PTT pour by-passer la boite (dans ce cas un seul des 2 dipoles est en service).

Another nice feature of the "Cizirf-special" is its capability to eliminate local QRN. This audio clip, recorded this morning on 40m, gives an example on a QSO between a ZL and a DL station. Although the antenna was not designed for DX, it may also help, if you are affected by local man-made noise. This recording has been made using the MFJ-1025 and a foot-switch connected to its PTT input, in order to by-pass the phasing box (in this case only one of the two dipoles is connected to the receiver).

The "Cizirf -Special" antenna in english

2008-01-20T10:39:00.000+01:00

This new video is to announce the English translation of the "cizirf-Special" antenna description. This is a broadband receiving antenna optimized for short an medium distances. The soundtrack has been recorded on 80m with I1 stations, located about 150 kms from home, just using a simple version only 1m AGL where the phase-shifts were obtained by means of switched coaxial lengths. On the video you can see the 80m patterns, simulated with NEC2 (4Nec2 by Arie Voors) for 0, 45, 90, 112.5, 135, 157.5, 180, 202.5, 225, 247.5, 270 and 315 degrees (the rotating one being for 125 degrees). This antenna was initialy designed with our "national contest" in mind, but I am sure you will find many other applications.
You may not believe the 30dB claim... then have a look at this video !

Alternative au UNUN: Le BB2

2008-01-19T14:14:00.000+01:00

Un grand merci à Jérome F4AJS pour le lien. Le lien ayant été tronqué dans son commentaire le revoila . Voila un coupleur, qui donne dans les 25 dB d'isolation pour 3dB d'insertion. Article de John Bryant and Bill Bowers daté de Janvier 2005 et publié sur le site DXing.info. Une bien meilleure solution que le coupleur résistif !

Une alternative très simple au UNUN

2008-01-18T07:36:00.000+01:00

Je tiens à remercier un lecteur attentif (mais très timide ;-) qui m'a signalé que le schéma publié hier était "una tonteria", la ligne allant du "combiner" à chaque antenne n'étant pas adaptée côté coupleur. Dont acte ! J'avais cependant raison sur un point, l'idée du "resistive combiner" n'était pas nouvelle! Ces "petites choses" sont utilisées en mesure, par exemple quand il s'agit de "combiner" deux générateurs (mesures d'IMD). Un coupleur résistif peut être réalisé avec 3 résistances de 16.6 ohms, en étoile comme montré sur la fig7 de cette doc. L'isolation entre ports n'étant pas terrible on leur adjoint généralement des atténuateurs (ou mieux des isolateurs) dans les branches allant aux générateurs. En partant du schéma 1, et en insérant 2 atténuateurs en T de 3dB, on arrive schéma 2, qui nous donne -9dB d'atténuation et 12dB d'isolation entre les ports 1 et 2. C'était donc pas si simple !
J'en profite pour lancer un appel: Visiblement tous les coupleurs hybrides dont on peut trouver les descriptions, sont plus ou moins "monobande" (générallement ils utilisent un circuit LC ou des tronçons de ligne). C'est ausssi le cas des coupleurs "Comtek" (comme le PVS-2). En revanche, Sylvain F6CIS, m'a signalé que dans références du catalogue de la maison ANZAC, on peut trouver un coupleur hybride 90degrés (ref jh-6-4) couvrant de 2 à 32Mhz. Quelqu'un aurait il une idée de la façon dont on pourrait réaliser ce prodige (juste pour ma culture perso...).
J'en profite également pour vous conseiller de rendre une visite à l'excellent site de TK5EP, où l'on peut trouver (entre beaucoup d'autres choses) une description assez détaillée d'un coupleur hybride 4 voies pour alimenter un "4-square".

Un UNUN 50/25 ohms en 5 minutes...

2008-01-16T09:26:00.000+01:00

La version 1: trop de tours pour l'indice AL de la ferrite... 1:1 sur 160m, 1.3:1 sur 40m

La question m 'ayant été posée, voici quelques idées pour réaliser un UNUN 25/50 ohms pour la Cizirf-spéciale. Un UNUN est juste un auto-transfo RF. Si l'on place une charge 50 ohms au borne d'un enroulement comportant 10 spires on va trouver à la 7ème spire un rapport de transformation en tension de 0.7 soit en impedance 0.7 au carré, soit 0.49 (dans l'idéal il faudrait un rapport de transformation de 0.707 en tension). Le premier a été réalisé sur une ferrite "à fort indice AL" (dont l'usage inital est le bloquage des courants de gaine sur un coax de 11mm) avec 5 tours bifilaires et une prise à 2 tours sur le second enroulement: Résultats SWR1:1 sur 160m, 1.1:1 sur 80m et 1.3:1 sur 40m.

Test de la version 1 la charge 25 ohms est constituée de 2 charges 50 ohms mises en parallèle.

Moralité trop de tours... (il faudrait une ferrite avec un indice AL plus faible). Pour le deuxième j'ai utilisé une ferrite plus petite (pour cable de 5mm) et trois fils torsadés, passant une seule fois dans la ferrite. Le port 50 ohms est connecté aux bornes des trois enroulements mis en série (attention au sens des enroulements) et le port 25 ohms (22.5 ohms en réalité) aux bornes de 2 enroulements: résultat 1.1/1 du 160m au 30m ce qui correspond au calcul puisque 50/45= 1.11
Pour réaliser le UNUN: si l'on suppose un fil noir, un blanc, un rouge. Le début du fil noir étant la masse, on connecte l'autre bout du fil noir (après son passage dans la ferrite) au début du fil blanc (avant son passsage dans la ferrite), et l'autre bout du fil blanc au début du fil rouge (les 3 enroulements sont dans le même sens et en série). On obtient le port 50 ohms entre la fin du fil rouge et le début du fil noir (la masse) et le port 22.5 ohms entre la jonction blanc/rouge et la masse. On peut bien sur mettre ça en boite avec 3 embases SO239, les 2 ports 50 ohms allant aux antennes, étant juste connectés ensemble, et reliés au port 25 ohms du UNUN. Je vous renvoie au bouquin de W2FMI (transmission line transformers), si vous voulez affiner le sujet... Bonne bricole!

La version 2: juste 1 passage dans une ferrite à fort indice AL. Le SWR mesuré est de 1.1 sur 160, 80, 40, 1.2 sur 30m et 1.3 sur 20m.

Cizirf-spéciale: Une version bidirectionnelle simple...

2008-01-15T14:13:00.000+01:00

Voici une version bibande et bidirectionnelle (*) de la Cizirf-spéciale: Elle ne demande qu'un relais (ou commutateur) coaxial, 2"T" coaxiaux (à monter en sortie du relais) et un UNUN 25/50 (lui aussi à monter au ras du relais). L'astuce consiste à utiliser 19.66m de RG8 (ou RG213 ou tout câble de vélocité 0.66) créant un déphasage de 252 degrés sur 40m (7.050), et 128 degrés sur 80m (3.600). Il va sans dire que les lignes allant du relais à chaque dipôle, doivent être de même longueur et constitution. La simulation (**) supposant une répartition égalitaire des courants entre les 2 dipôles il faudra s'assurer que ceux-ci sont parfaitement identiques, et qu'ils exhibent un SWR aussi bas que possible sur les 2 bandes (au besoin il faudra retoucher la longueur des éléments et/ou la valeur des resistances d'amortissement). L'antenne a été simulée avec 15m d'espacement entre dipôles et 7m de hauteur, mais 1m/sol peut faire l'affaire si l'on dispose d'une réserve de gain suffisante sur le récepteur.
(*) Une idée subite, non encore testée...
(**) les diagrammes horizontaux sont donnés pour 45 degrés d'elévation. En rouge le diagramme 80m, en bleu le 40m.
Vous pouvez cliquer sur les images pour les agrandir.

Radio Sloboda and the "Cizirf-special"

2008-01-15T09:18:00.000+01:00

Voici un lancement "à l 'américaine" pour vous signaler que la description complète de la "Cizirf-spéciale" est désormais disponible en suivant ce lien
This is an "American style" advertisement for the "Cizirf special", a receiving antenna optimised for short and medium range communications on 40 and 80m. The complete description including simulations, pictures and the results of many "on the air tests" will be made available soon in english on this blog. Have you ever dreamed about 30dB F/B even at high angles? Then this antenna is for you...

Petit banc-d'éssai de la MFJ-1025

2008-01-14T09:34:00.000+01:00

La MFJ-1025 que vous avez pu voir en oeuvre sur les vidéos réalisées à la station souffre, à mon avis, d’un certain nombre de faiblesses :
- Elle ne permet qu’une plage de 0 à 130 et de 180 à 310 degrés de variation de phase, ce qui est insuffisant (il faut ajouter un bout de coax « commutable» pour couvrir les 50 degrés manquants de part et d’autre, le dip recherché se trouvant quelquefois dans cette zone).
- Elle à un gain négatif. On trouvera sur la page de W8JI consacrée à cette boite, quelques modifications, pour améliorer un peu les choses.
- Son facteur de bruit ne permets pas l’utilisation d’antennes délivrant un trop faible niveau (j’ai du monter mes deux dipôles amortis à 7m, pour couvrir le bruit introduit par la boite). Il faudrait lui adjoindre 2 préamplificateurs , par exemple ceux décrits par W7IUV
- Elle demande des doigts de fées pour les réglages et des doigts de dockers si on veut espérer tenir un contest (les potars étant assez « durs »). De plus il faut un certain entraînement pour en tirer les résultats espérés, l'équilibrage en amplitude des deux antennes variant sensiblement avec la phase.
La NCC1 de DX-engineering, est assurément beaucoup mieux conçue tant sur le plan performances, qu'ergonomique. Elle est certes plus chère, mais je pense que la différence de prix est justifiée. Le seul reproche qu'on peut lui faire d'après F6CIS et F6IRA qui l'ont testée à F6KNB, c'est une protection insuffisante des entrées lors du passage en émission.
Pour un utilisation "contest" on peut cependant regretter qu'aucune de ces boites ne comporte de "presets" autorisant une mémorisation des réglages les plus utiles.

Castres, dans le 81

2008-01-14T08:45:00.000+01:00

Une petite dernière pour la route! Comme dans la vidéo précédente "ça va faire mal !" la phase est ajustée pour une réjection des signaux venant de l'Est. On peut observer les effets de l'inversion de phase sur le "spectrum-display" du pro2.

"Cizirf-special": Rapport avant-arrière sur 40m

2008-01-13T19:47:00.000+01:00

Réalisé dans les mêmes conditions que la vidéo précédente (sauf que comme on peut l 'entendre je peaufine la réjection), voici un "petit" enregistrement réalisé cet après-midi sur 40m qui montre le rapport avant-arrière qu'on peut espérer obtenir avec la "Cizirf-special". Je pense que je n'ai même pas besoin d'indiquer quand j'inverse la phase des deux dipôles, car à vue de nez le rapport avant-arrière est de l'ordre de 25dB (de S9+10 a s3 sur le s-mètre du pro2), c'est donc assez évident ! Pas trop mal, pour une antenne aussi bon marché et aussi vite faite!
Je vous en ai mis que les 3 dernières minutes, mais l'OM a causé non-stop pendant au moins 15... Aussi pratique qu'un broadcast pour tester les antennes !
A noter: J'ai du "detuner" ma verticale 40/80, car le dipôle "Est" qui passe a environ 2m de la verticale, me rammenait quelques 10dB de plus de bruit que le dipôle "Ouest". Dans ces conditions, le rapport A/AR était sérieusement dégradé. Le précepte disant que les antennes de réception doivent se trouver le plus loin possible des antennes d'émission, n'est donc pas un mythe !

Ça va faire mal...

2008-01-13T12:11:00.002+01:00

Ça va faire mal, comme dit F2FZ sur cet enregistrement réalisé sur 80m ce matin ! Ce qui est intéressant ici, c'est que j'ai utilisé un réglage général permettant d'atténuer les stations situées dans le secteur Est. On peut noter, que même sans aller chercher un dip très pointu comme sur la vidéo précédente (difficile à faire en contest!), on peut obtenir une amélioration sensible du rapport signal/bruit. La "cizirf-speciale"est toujours E/W, à 7m et avec un espacement de 15m. La description complète de l'antenne est en cours de correction. A suivre...

No comment...

2008-01-11T22:19:00.000+01:00

Juste quelques uns quand même: Cette vidéo montre le rapport avant-arrière qu'il est possible d'obtenir avec la "cizirf-speciale", quand on peut jouer finement sur la phase et l'amplitude. Le jeu consiste à obtenir la réjection maximum, et à switcher la phase de 180 degrés pour obtenir le maximum de signal. Les 2 dipôles amortis sont à 7m/sol, espacés de 15m et orientés E/W. Je reviendrai sur les détails dans l'article à paraitre sur ces pages... En attendant voici d'autres demos audio obtenues dans les mêmes conditions:

Démo 1: Enregistré ce matin sur 80m. Comment se débarasser des splatters d'un QSO DL à 1.5Khz de la fréquence. J'ai ajouté des "bips"au moment où j'enfonce le bouton 180 degrés du MFJ-1025.

Démo 2: Enregistré hier soir sur 80m en debut de soirée. Comment sortir un QSO "National" du bruit de la bande quand la propagation est à longue distance...

Démo 3: Enregistré hier soir sur 40m. Comment se débarasser d'un QRM particulièrement virulent (s9+ sur la verticale).

A Suivre: un banc d'essai du MFJ-1025, et l'article complêt décrivant la cizirf-spéciale avec toutes les options... Merci pour vos nombreux emails d'encouragement, mais n 'hésitez pas à laisser des messages sur ce blog.

Une antenne de réception NVIS - 2 Vidéos

2008-01-09T10:28:00.000+01:00

Une video vite faite, dans les mêmes conditions que les enregistrements précédents: l'antenne 1 est la verticale, l'antenne de réception "la cizirf spéciale" les 2 antennes étant équilibrées en niveau sur le bruit de la bande. L'analyseur de spectre est centré à 3650kHz, la fréquence écoutée est marquée d'un trait rouge.En jouant avec la phase, on peut obtenir une atténuation intéressante des signaux arrivant par l'arrière, ici sur une station Belge (environ 500 kms). Le système utilisé est très simple, il consiste a insérer des lignes de coax. pour retarder la phase de l'antenne avant. Le système décrit dans ce pdf, permet sur 7Mhz de faire varier la phase de 0 à 157.5 degrés par pas de 22.5 degrés. Ici le signal le plus fort est obtenu avec les 2 antennes en phase et le minimum pour 135 degrés, mais si la station se trouve vers l'avant, on obtient l'effet inverse, comme l'atteste cet enregistrement réalisé sur 40m quelques minutes après la vidéo. On peut quelquefois obtenir des résultats surprenants, comme sur cet enregistrement 80m de deux stations I1 situées juste vers l'arrière de l 'antenne, quand celle-ci était montée WNW/ESE. Ce dernier exemple est particulièrement exceptionnel si on considère la simplicité du système mis en oeuvre (en géneral l'atténuation est de l'ordre d'une douzaine de dB's), mais en faisant varier phase et amplitude "en continu", il devrait être possible d'obtenir quelque-chose de similaire assez fréquemment. A suivre...

Une antenne de réception NVIS "la Cizirf-spéciale"

2008-01-08T15:58:00.000+01:00

Un des dipôles et la verticale utilisés pour cet éssai.

Voici les résultats des premiers éssais réalisés avec l'antenne de réception dont j'ai exposé le concept dans l'article "Quelle antenne pour la coupe du REF ?" . Après différents éssais de hauteur et d'espacement, l'antenne a été montée a 1m du sol, avec les 2 dipôles distants de 25m (0.6wl sur 40m).

L'antenne a d'abord été testée sur un QSO local 80m. Ci dessous la liste des stations figurant dans l'enregistrement ainsi que les différences de niveau notées d'après l'audiogramme de l'enregistrement (réalisé avec la CAG bloquée, et les 2 antennes equilibrées en niveau sur le bruit de fond).

F5IOG 505 kms 15dB, F6HXU 38kms 30dB, F1AVW 162kms 20dB, F1RGX 162kms 20dB, F6BXL 54kms 25dB, F1GCX 4kms (mais pas a vue directe) 0dB

Sur 40m, le seul QSO Francais entendu, impliquait des stations situées entre 479 kms (F5ODW/33) et 607 kms (F6CTT/35). Le début de l'enregistrement montre l'équilibrage du bruit de fond sur les 2 antennes. A ces distances, les différences sont moindres mais toujours intéressantes (10 à 15dB). La fin de l'enregistrement est particulièrement intéressante, car j'introduis 90 degrés de retard de phase dans l'antenne avant (les 2 antennes étant tournées en direction de F5ODW). On constate sur l'audiogramme que le signal monte d'environ 4 à 5dB (dûs à l'inclinaison du diagramme de rayonnement).

Enfin voici une démonstration de l'utilité potentielle en contest domestique... Au moment ou la station DL et F5NMK transmettent simultanément, la commutation de la verticale à la Cizirf, permet découter l'un ou l'autre. A noter que même F9OE/P29 (la station F potentiellement la plus lointaine que je puisse trouver) arrive sensiblement mieux sur l'antenne NVIS que sur la verticale. Il faut juste pondérer par le fait que la verticale fonctionne en 1/2 onde sur 40 avec un lobe relativement étroit centré à 22 degrés d'elévation. J'attends toujours la livraison de la boite MFJ pour compléter l'article... A suivre donc, mais comme disait le regrété Desproges "étonnant non ?".

Quelle antenne pour la coupe du REF? audio-clips

2008-01-06T15:20:00.000+01:00

le "broadband-dipole" utilisé pour cet éssai (cliquez sur l ímage pour l'agrandir)

Suite à la 4 ème partie de mon article , présentant des antennes de réception, et pour ceux qui douteraient de l'intérêt d'un dipôle à très faible hauteur comme antenne de réception NVIS, voici quelques clips audio. L'antenne 1 est la verticale décrite dans ces pages, l'antenne 2 est un "broadband-dipole" non résonnant de 2x15m à 4m de hauteur.

Test1-40m Test2-80m Test3-80m Test4-160m

Quand il s'agit de stations F, Le dipôle est systématiquement l'antenne offrant la meilleure qualité d'écoute. La version améliorée, "la cizirf spéciale", composée de 2 de ces dipôles dont on fait varier la relation de phase est en cours de test à 2 endroits distants de l'héxagone. Une description complête incluant les résultats de ces éssais paraitra prochainement sur ces pages.

Le dipôle large bande: un balun 1/4, une résistance de 270 ohms et deux fois 15m de fil de 0.5mm...

What's up Doc ?

2008-01-03T20:54:00.000+01:00

Nada! - juste pour spotter une sélection subjective d'articles parus sur ce blog depuis août 2005. en principe les plus intemporels et les plus techniques... C'est ici !Mais si vous avez la patience de fouiller les archive du blog, vous trouverez plein d'autres trucs, comme cette photo prise au cap-corse, en 2001 lors de l 'ARRL-10m alors que nous venions d'essuyer une tempête et que ça soufflait encore très fort !

Quelle antenne pour la coupe du REF? suite et fin

2008-01-01T11:21:00.000+01:00

Une bonne et heureuse année 2008 ! La 4ème et dernière partie de l'article est diponible en suivant ce lien.

Quelle antenne pour la coupe du REF? suite

2007-12-30T08:57:00.000+01:00

Jamais un post sur ce blog ne m 'avait valu autant de courrier, commentaires et suggestions ! Merci à tous.
La partie 3 est désormais disponible ici
Je suis en train de rédiger une partie 4, qui traitera d'antennes de réception optimisées pour la CDR. Si vous avez des idées et/ou des suggestions que vous êtes près à partager, n'hésitez pas soit à poster sur ce blog (avec un lien vers votre page ou une autre page intéressante), soit à me les envoyer par email. Bonne année 2008 à tous...

Quelle antenne pour la coupe du REF?

2007-12-26T10:41:00.000+01:00

Voila un petit article pour les adeptes de la Coupe du REF. Il s'agit d' une petite étude basée sur des simulations réalisées avec VOACAP, et qui devrait vous permettre d'optimiser vos antennes pour ce contest si particulier. On peut consulter l'article en suivant ces liens:
partie1 partie2

TM6A CQWW-CW 2007 a few more 80m audio clips

2007-12-03T08:52:00.000+01:00

If you can't hear them, you can't work them ! I worked 45 "zone 3" stations during the contest, despite the reported "bad conditions". Here are a few of them. A few QSO's are pretty much like EME ! A special mention to our friend Dick W7ZR from Arizona, met last march in Casablanca.
CN8PA, W7EJ, W7ZR in CN2R station, last march after the WPX-SSB

A selection of AS and OC QSO's. Here also a few ones are very close from EME qso's (when they were done random on CW !). You may note the difference between the NNE beverage and the ENE one on the QSO with VK6HD (i switched to the right beverage only at the end of the QSO, when Mike was sending his zone). There is only 30 to 35 degrees AZ between the 2, but it makes quite a difference !

CQWW CW Contest - TM6A - audio clips

2007-11-29T17:47:00.000+01:00

Unfortunately, due to a bad configuration of the MK2R, I recorded only the main radio during the contest. However this recording, made at home using one verticaly and an one horizontally polarized antennas, gives an idea of the benefit which can be expected from the "antenna diversity" in the headphone. Obviously you have to listen it in stereo, and preferably using a headphone.

This audiogram, shows one of the problem I experienced and slowed me down a bit: The 600ms delay between the last transmitted dash and the return of the RX, is defenitely too long, and generated quite a few "prefixes" misses (as you can hear in the following recording). As a security, I just used Joseph's sequencer (which protects the RX and the beverage preamp) on the "PA-PTT" output of the MK2R... I should have looked at this more carefully before the contest !
10mn of the second hour, with a good rate (>200). As mentionned above, quite a few prefixe repetition requests could have been avoided by optimizing the RX return time... my mistake !

Beyond the QRM made by my compatriots, starting a +170Hz from my freq, the benefit of the diversity receive is illustrated on the QSO's with W1TO and EA4AYD (only the "beverages receiver" is recorded here). Nothing was audible from W1TO before I switched to the NW beverage, but I heard him calling on the delta in my left hear... the same for EA4AYD, who was too QRM on the beverage, but perfectly audible on the transmit antenna.

TM6A @F6CTT CQWW-CW 2007

2007-11-29T07:56:00.000+01:00

Claimed summary
Category: SOSB80 HP
Total: VQ:2382 ZN:33 CTY:115 Total Score = 638,324
ALL===EU===AS===NA===SA===AF===OC
2472==1440=120==867==19===16===10
=====58.2%=4.8%=35%=0.8%=0.7%=0.4%
With Gisele in Saint-Malo one week before the contest. Who said it is always raining in britanny !
The story starts with a SSB-QSO with joseph on 160m. I had already planned a week holiday with my wife in Britanny, when Joseph offered me the chance to use his station for the contest. The 20m antennas being down I had the choice between SOSB40, 80 and 160... Don't ask me why I said 80, but this was my choice ! (maybe because I knew that Joseph had made a big score during the SSB-leg, so this was a guarantee that the station was working fine on this band !). Anyway, when you have a host like Joseph, you don't have to worry... I phoned him during the week and he had already retuned the TX-antenna in the middle of the 80m CW-band. On my side I had tested a "diversity receive" concept that I had in mind for a few months and everything was ready, so it did take less than one hour on friday afternoon to be ready with my Icom transceivers, the MK2R+ and my usual laptop and software !

Joseph's contest site (when all the antennas were up !) (photo F6ARC)

All the logistics and antenna aspects being already "tested and approved", I could focus on "new stuff to be tested". Having some experience with VHF contesting, I knew that switching RX antennas to find the best one for each QSO is not only tiring, but it may also significantly slow-down your run... On the other hand not using the beverages (or only using them from time to time to pick-up a weak station) would increase the proportion of 1 point-stations vs the 3pointers. So why not applying the SO2R technics to antenna diversity ? In short, a different RX/antenna in each hear. The idea, was that when the callers are strong enough, you dont want to loose time and energy to switch the receive antennas and you use your both hears on the "best beverage" only when the signal is just above the noise. I must say that it did work quite well ! The "spatial stereo" provided by the 2 receivers also helps to discriminate calls in a pile, as well as some antifading (it is not rare to have one station moving left to right and right to left, with the QSB) . There are still a few things to be improved (like optimizing the RX return-time, limited by RX and Bev-preamp protections), but overall, I think that it provided a real bonus (at F6CTT the beverages are so efficient, that you may miss a relatively strong station calling from an unexpected direction...). I also tried 1 beverage in each hear, for a couple of hours, but I came back to the 1st solution, the delta being not such a bad RX-antenna and the South-sector beverages a bit too noisy.

Myself in the same station for the same contest, but in 2002 for TM5C M/S. (photo F6ARC)

Having no cluster, I also used, the second receiver for mult-hunting during run but this is a bit tiring and frustrating, so only during a few limited periods - In SOSB80, the number of "potentialy workable stations" being somewhat limited, I don't think you loose very much by breaking the run on a a regular basis for a 30mn S&P period and in CW, finding a 400Hz free-slot for returning to Run is not such a difficult task.I started on time and the first 4 hours of run provided near to 600 QSO's with a 163 "peak"during the second hour. I then broke the run for 40mn S&P period which provided 15 countries and 3 new zones. Logged my fisrt ZL at 0703 and the QSO #1000 around 0900z, just before going to bed. I came back at 15z. during the second period, the rate never went above 100, so I spent more time S&P'ing .

The beverages are the key of success at F6CTT, there are 5 long terminated beverages, pointing NNE, NEE, SE, SW and NW.(photo F6ARC)

I found my first JA at 1608z and worked the first VK at 2112. Ended the second period at 0903z with QSO #2050. Started around 1530Z and worked OX at 1553 (this was an unexpected direction !). The last period provided a slow run not exceeding 70, but a few good suprises, 4 being "double multipliers" (from zones 26, 27, 30 and 38). I particulary appreciated the "trouble-free" operation, the quietness of the site, to have to use the foot-switch only for paddle-keying and on top of the rest the quality of the mattress ! Again thanks to Joseph for his hospitality and for giving me the opportunity to use one of the best contest site in France. This was not CN, but still a lot of fun...

CQWW CW Contest - TM6A

2007-11-14T08:51:00.000+01:00

For the CQWW-CW, I will be active from F6CTT station, with the special callsign TM6A. Unless last minute technical problems, the category will be SOSB 80m. CU in the contest !

Please note: Electronic confirmation via LOTW, conventional card only via EA7FTR.

Propnet "POP" 30m weekend summary

2007-10-10T15:42:00.000+02:00

A full report on the 30m "play on PropNet" weekend is now available by following this link

Propnet 30m weekend

2007-10-08T11:24:00.000+02:00

For once a non contest activity !

This weekend I participated to the propNet 30m weekend, a 30m propagation study. For more details on the propNet project, you may follow this link or this one

Here is a first summary of the weekend activity. More to follow...

Another vertical for 30, 40, 80 (and 160)

2007-10-03T07:04:00.000+02:00

Following is a description of the multiband vertical antenna that I am using for several months.

Description in english

Une verticale pour 30,40 et 80m

2007-09-26T13:21:00.000+02:00

Ca faisait quelques temps que ce blog n 'avait pas été mis à jour ! Désolé...
Voici, pour me rattaper une description de l'antenne verticale bande basse que j'utilise depuis quelques mois.
Article en Français

CN5W - Dar Bouazza Contest Group

2007-03-28T17:17:00.000+02:00

The contest stories, pictures, stats and more are on
http://cn5w.blogspot.com/

The CN2WW 80m wire-beam

2007-02-24T19:38:00.000+01:00

After testing the concept last year in the ARRL-DX from home (see http://f6irf.blogspot.com/2006/02/low-cost-2-elements-for-40m.html ) I designed a new antenna, especialy for the ARRL-DX from CN2WW. The terrasse dimensions, limiting us to 8m spacing, I used a director rather than the classical reflector. The drawing shows the 2 beams (40 and 80) using the same supports. Obviously with a such a reduced spacing (0.1 wl), the antenna cannot be designed for z=50 while giving satisfactory performances, but using a UNUN provides a perfect and broadband match, with very low losses (The steppIR uses the same type of broadband matching device). The multi-UNUN based on a W2FMI design and commercialized by CWSbytemark ( http://www.cwsbytemark.com/ ) offers an easy and flexible solution. A second unit allowed the 40 beam to be designed for max gain, with impedance around 36 ohms. The only difference is that the 40m UNUN was placed after a 1/2wl of cable, and not directly at the feed point ( the 40m dipole being on a fiber mast). The following graphs show the performances of the 80m aerial.

The bandwith was the main concern, but as shown by the graphs most of CW-contest band is usable with SWR below 2. Although I have full confidence in computer simulation, the results obtained with this aerial during the ARRL-DX really surprised me. see http://lists.contesting.com/archives//html/3830/2007-02/msg01551.html ). I believe that on top o f the 3.5dBd gain its main quality has been to protect us from the heavy EU-QRM.
View of the aerials installed at CN2WW, the fiber mast supports the 40m dipole and the 80m director while the tower supports the 40m reflector and the 80m dipole.
As information the dimensions provided by the computer model are the following one: For 8m spacing and a center angle of 120 degrees, the half-dipole is 21.18m and the half-director 20.6m. But of course the dimension may vary, fonction of the height, the angle, the environment, the wire used (i.e. plastic coated wire has a velocity factor in the order of 0.95), so it is strongly recommended to adjust the dipole alone first below the desired frequency (removing the director on the computer model gives 3.465 for jX=0) Then place the director and cut it until the desired frequency is obtained (3.532 for jX=0 ). I think that it is the best way to get the aerial working as expected.
Computer models (MMANA or NEC2) can be provided on request.

F6IRF 100,000 QSO's in 5years

2007-02-04T09:09:00.000+01:00

Today I have uploaded the 100,000 QSO, since march 2002 to LOTW. Those include QSO's done with F6IRF, F6IRF/P, TM6A, IS0/F6IRF, FG/F6IRF, UT/F6IRF/P and CN2WW callsigns.
DM6DL is the 100,000, and wins a CN2WW Tshirt :-)

IC7000 review

2007-01-30T02:54:00.000+01:00

The good the bad and the ugly !
Recently bought this TRX for travelling around for contests and to replace my 706 which did not have the adequate CW/RTTY filtering for contesting...
Weight= 2.3kgs, was also one of my motivations, taking into account the new limitations for hand-carried cabine luggage!

Tried this weekend in CQWW-160 and REF-test

THE GOOD
- Being familiar with the 706, it did not take long to get familiar with it... a few things have changed, but the user interface philosphy, remains moreless the same.
The display is really bright and contrasted and does not require that I put my glasses on...
For a CW-contester RX DSP-Filtering is really the strong point of this transceiver, together with the usual ICOM strong points (I am also owner of 756pro2). The "strong signal" resistance is not as good as my pro2, but sure better than the 706 (ie on 706 the preamp was unusable on 20m and the attenuator often required on 40)
A few have reported temperature problems... did not see this even during long sterile auto-CQ sequences with 3s RX-time. The temp indicator always remained in the blue zone (Had even tried 4 hours of the same regime at full CW-power on a dummy load B4 the contest - no problem...). Haven't tried yet in TTY... will see!

THE BAD
- Do not like the RIT/XIT on the coaxial pot... even more unusable than the 706 RIT (why not the main dial when selecting RIT like in the Yaesu FT857D. It Would be far more convenient !). Of course it is possible to use the split, but there is always a risk to move the TX freq, especialy when using auto-CQ from your contest software.
- A pity that the local-monitoring (CW-sidetone and SSB-monitor) is not available from the fixed-level audio output on the ACC connector (if you record your pile-up through this line, you won't have your own signal !)
- The RF-power output is a bit "limited": From 95W on 160 down to 80W on 10m and 75W on 6m (but will check this again with a professional wattmeter). Not a problem when using a modern tetrode PA or an SSPA, but a bit just for entering LP-category (especialy in those contests for which LP is 150w

THE UGLY
- The long spotted "audio white noise" is really annoying with a normal headphone without pots. It becomes acceptable with audio-pot around 11h, so will make an external attenuator / low-pass filter for the next contest, but it is a pity that Icom did not fix this pbm, despite all user-complaints (maybe for the PRO version!?). Maybe another solution is to use a vintage low sensitivty/limited bandwidth headphone.

SUGGESTIONS FOR THE PRO VERSION
- Improvement of the a/m BAD and UGLY features
- Why not make the second SO-239 connector (dedicated to VHF/UHF) usable for a second HF antenna and/or a RX antenna (it sure would be appreciated by 160m freaks !). It could be done from the main setup menu (disabling VHF/UHF, if required)
Of course this is a CW-contester/DXpeditionner point of view which may not be relevant if your main use is as mobile-rig... Despite the few a/m problems it is definitely a good choice for a small TRX, so I give it 4/5.

Regards and 73's

Patrick
F6IRF/CN2WW

F6IRF in CQ ham-radio (JA)

2007-01-09T10:56:00.000+01:00

Thanks to Hisami 7L4IOU for sending me the October 2006 issue of the Japanese magazine CQ-ham radio.

F6IRF/P: A bit of traffic from South Britanny

2007-01-08T15:47:00.000+01:00

Stew Perry Topband Challenge
Call: F6IRF/P
Operator(s): F6IRF
Station: F6IRF/P
Class: Single Op LP
QTH: IN87
Operating Time (hrs): 8
Total: QSOs = 112
Total Score = 1,416
IC756pro2 -100W
inverted-L on 2x 12m fiber masts

One of the 12m mast used to support the 160m inverted-L

Part-time effort, just to enjoy the low-noise level of my secondary QRA on a band which is usualy forbidden for me due to the HT-line hi-noise level at my main location. Quite a few DX stations heard, but none logged...
Une participation en diletante, juste pour apprécier le calme radio-electrique du QRA secondaire, sur une bande qui m'est habituelement "interdite" en raison,du fort bruit de fond généré par la ligne 380kV qui jouxte le QRA principal. Pas mal de stations DX entendues, mais aucune contactée...Les condx ne semblaient pas terribles, aucune station W/VE dans le log, alorsque j'en ai assez facilement contacté qqs unes pendant la semaine...Stn: IC756 et antenne L-inverse sur 2 mats en fibre de 12m. (pas de radians...juste le grillage entourant le QRA en guise de contrepoids...)QTH: Arzon, dpt-56 (au bout de la presqu'ile de Rhuys, entre golfe et ocean...)

Above, the mast, also supporting a 30m dipole, and here the R7 antenna

I have been active all week, mostly on 160, 30 and 17m both in CW and digital modes...
CN2DX on 160m, recorded fm F6IRF/P (CW and SSB)

Phasing / Unphasing 2 yagis - Solution and benefits

2006-12-25T13:55:00.000+01:00

Having 2 yagis at home for SO2R-contesting, I quickly realized that it was sometimes very useful to use the 2 antennas on the same band. For example, during summer, the 20m band is still open to Asia, simultaneously with North-America. Having one antenna in each direction, just switching from one to the other, was the obvious first step. Then logicaly, the idea came to feed them both... I first used a "UnUn" to match the antennas fed in parallel, but this solution although working fine was lacking flexibilty. I then decided to buy a "stackmatch" allowing to use one or the other, or the 2... Using this device, I quickly realized, that the phase relashionship between the 2 antennas was essential, and that the antennas being not identical and not in the same plane I had to be able to play on the phase relationship between the antennas. I then looked for some commercial solution or description, but could not find any(*); I then decided to quickly build something, and try it...

(click on diagram to enlarge it)The F6IRF antenna monoband phasing device: It just requires 3x2RT switches. Phase delays are obtained using 3 lenghts of coax cables 1/8wl (45degrees) 1/4(90degrees) and 1/2 (180degrees). Combining the 3 allows 0 to 315 degrees variation by 45 degrees steps. The device is inserted in one of the antenna line, after the stackmatch. I have used 5D-FB foam coax cable, and high-current switches (losses and impedance mismatch are neglectable and it was tested at 1KW without problem...)

The phasing device in service, during the 2006 CQWWDX-contest from CN2WW (SOSB20m).
From Morroco, it is a big advantage to keep one antenna toward EU, while playing with the second one, to get mults in exotic directions, or to boost the EU rate, with the second one toward states...

Potential applications and benefits

First example: The 2 antennas at 12m are in the same plane pointing at the same desired direction and spaced horizontaly by 0.8wl (my home setup to JA). As shown by the following examples, varying the phase allow some direction adjustment, which is quite useful as the horizontal pattern is quite narrow (even with the simple 2elements used for the simulation - just imagine with 2x 5 elements).

Click on images to enlarge them. Here, the 2 antennas are at 12m agl, in the same plane, perpendicular to the desired direction, spaced by 0.8wl and fed in phase (I.E. identical antennas with equal lengths of coax cable). In red is the pattern of 1 antenna, in black the pattern of the stack. The gain of the stack is 3dB compaired to a single antenna, but the pattern becomes quite narrow.

Left: the antennas are fed with 90degrees relationship (in red the pattern of a single antenna as reference). Right: The antennas are fed with 180 degrees relationship, the pattern becomes bidirectionnal, with a nul in the main direction (in blue the pattern of the antennas in phase, in red a single antenna). By varying the phase, it is therefore pssoible to adjust the pattern to any value between +/-30degrees compaired to the perpendicular axis of the antennas.

Second example: the 2 antennas are not in the same plane, and one antenna is turned by 45 degrees...

right: The pattern of each antenna fed separatly. To be noted, the backlobe of each antenna is distorted by the presence of the other one.

Left: one antenna phased out by 45degrees, the result (in black) is almost a virtual antenna pointing between the 2. Center: the phase relation is 225degrees, the bidirectionnal pattern is almost restored. Right: the phase relation is now 315 degrees, the bidirectionnal feature remains but with a substantial advantage for one of the antenna.

Third example: Here the 2 antennas are pointing at 90 degrees directions; you may think that the phase relation is less important in this case... it is, but still, it is not completly useless to play on the phase...

center: the 2 antennas are fed in phase, the expected bidirectionnal pattern is here, but with some distorsion (in red the pattern of a single antenna)The 3dB loss is normal taking into account that each antenna is fed with half of the power. Right: In black the 2 antennas are fed with 180 degrees phase relationship (in red, the antennas in phase, in blue a single antenna as reference).

Fourth example: Like in example 2, the 2 antennas are looking at 45 degrees directions, but it is the second antenna that has been turned (as shown in picture below).

Left: the patern of each antenna fed separatly. Right: the patterns obtained when phasing the 2 antennas with 0, 90, 180 and 270 degrees phase relationship.

Comments : This system was built-up for 20m band, however, it is also usable on 15 and 10 (with 90 degrees step on 10 and something in between on 15). It is also usable on 40 but then the phase limit is 315/2=157.5 degrees. Of course it is possible to add lines and switches if you are interested by multiband capability, but the spacing of the antennas will have to be somehow "compromised", especialy if you are looking for "extra gain"(as shown in example 1). All simulations have been done using MMANA203 by JE3HHT and can be verified using NEC2 engine for MMANA by UA3AVR (allows MMANA antenna files to be converted to NEC2 files).

Does it work ?: The answer is yes ! just moving one switch maybe sufficient to get a station out of the noise and QRM, and this has been verified in several contests....
(*) To be accurate Array-solutions commercializes a "180degrees-unphaser" which allows high angle radiation for verticaly stacked yagis.

Above my home setup used in 2005 in more than 30 contests (a 2elts steppIR and an OB6-3M). Here the setup used at CN2WW for the CQWW-CW 2006 (SOSB20 - 3 elts SteppIR and 3elts spiderbeam) .

The maa and nec files are available here
http://mangafight.free.fr/2x2elts%20maa%20and%20nec.zip

Une version Française est disponible ici en pdf
http://mangafight.free.fr/Phaser.pdf

CN2WW - On the road again !

2006-10-10T22:44:00.000+02:00

Je serais de nouveau actif depuis le Maroc avec l'indicatif CN2WW à l'occasion du prochain CQWW DX CW, en principe en catégorie SOSB20m. Le QTH sera le même que l'an passé (Dar Bouazza, depuis la station de CN2DX). Activité peri-contest du 22 au 29 Nov; QSL via EA7FTR. Plus de détails à suivre...
I will be active once again from Morroco, with CN2WW callsign for the next CQWW DX CW. In principle I will take part in the SOSB20m category.The QTH will be the same as last year (Dar Bouazza, from CN2DX location). Peri-contest activity fm Nov 22 to 29; QSL via EA7FTR. More details to follow...

CQWW RTTY - DQ4W / TM6A MULTS ANALYSIS

2006-09-26T10:35:00.000+02:00

Just for the fun I took the BCC station, DQ4W claimed score published on 3830 for reference ( see http://lists.contesting.com/archives//html/3830/2006-09/msg00957.html )
Although they did more QSO's (2485 vs 2321), which is quite normal taking into account their M/2 category, I was surprised to see that we managed slightly more mults (590 vs 581) despite our poor location, and quite modest antennas.
Multipliers by type... States/prov is our weak point !

Of course, it could be explained by a collateral effect of the M2 category, but what is interesting is that we managed more zones and DXCC's but less states/prov. The effect of our poor take-off toward NA is quite obvious in the following graphs: On 80m, the 8 degrees blocking does not look as a major handicap, but it becomes dramatic on 15m... Conclusion: F6KAR maybe a decent location for many contests along the year, but certainly not for an ARRL-DX all-bands !

Multipliers by band... 15m is our weak band !

States/provinces by band: The effect of 8 degrees blocking !

TM6A @F6KAR - CQWW RTTY

2006-09-26T05:54:00.000+02:00

F6KAR 3D view toward ESE, first mountain is "le saleve"(1500m) and behind "le mont-blanc" (4807m). F6KAR station is located near the F/HB border.

Bd QSO Pts Sta DX Zones
------------------------------------------
80: 345 743 20 50 14
40: 659 1550 35 87 28
20: 970 2428 52 108 35
15: 311 731 13 83 27
10: 36 75 0 31 7
------------------------------------------
Total: 2321 5527 120 359 111
Total Score = 3,260,930

Club/Team : Cern(*) Amateur Radio Club (F6KAR)
StationHigh bands station: IC756 + Ten-tec Titan
Low bands station: IC756pro3 + Ten-Tec Titan
Ants: 80m: shunt-fed tower 40m:
40-2CD20-15-10: KT34 and 3el ECO
RX ants: 100m beverages NE and S, K9AY loop
Software: N1MM Logger V6.9.6 with MMTTY soft-terminal
MSC: ICE band-filters, microkeyer USB-conterters
station pictures here:
http://f6irf.blogspot.com/2006/08/f6kar-waedc-cw-2006.html

Operators: Nico F5VIH/SV3SJ, Phil F6IFY, Pat F6IRF
Guest ops: PM HB9DTM/F6FNL, Seb F8CMF

Condx better than expected taking into account the very low SFI
(who could expect 124 countries to be logged this weekend in TTY?)
15m opened to Eastern-states on saturday, and 20m remained open quite late.
Unfortunately the propagation deteriorated on sunday, but the E's openings allowed 31 countries and 7 zones to be logged on 10m.
Good first night with 2 hours at rate >80, but bad second night with rate droping around 20 between 2 and 5z and very few NA-stns. No major technical problem experienced, just a few glitches with PA switching and software behavior, both probably due to some RF-feedback.
Finaly a decent score for the solar minimum, thanks to DX-peditioners and all participants for creating such a huge activity on the digital bands (and even a bit outside ;-) !

F6KAR 3D view toward NW, "le Jura"(1500m) represents some 8 degrees blocking toward NA

(*)CERN is the European Organization for Nuclear Research, the world's largest particle physics center. http://f6kar.web.cern.ch/f6kar/
see http://press.web.cern.ch/public/

For Dan Brown readers see also;-) http://press.web.cern.ch/public/Content/Chapters/Spotlight/SpotlightAandD-en.html

see 3830 post for multipliers stats
http://lists.contesting.com/archives//html/3830/2006-09/msg00985.html

F6KAR - WAEDC, Stats and audio-clips

2006-08-16T11:08:00.000+02:00

WAEDC audio clip QTC'S - 21MHZ RK9CWW, EX2M, RN9SXX 28MHZ RW9QX, RU9CK, 9M6XRO
WAEDC audio clip QTC'S - 21MHZ UA9CDC
WAEDC audio clip QTC'S - 21MHZ CE3BFZ, PV8DX, CN8YR
WAEDC audio clip QTC'S - 14MHZ K6XX, VE3NE, KU8E, VE9DX
Click on the loudspeaker to listen to the clip. Click on the image to enlarge it...

qso's by time: not a contest to beat records !

qtc's by time: No good score possible without QTC's

Multipliers: hard to find, hard to work ! (multipliers are weighted 2x on 10-15-20m / 3 on 40m / 4 on 80m)

QSO+QTC by hour, the rate to look at...

Continents all bands: another contest where working NA is the key to success.

Continents by band: 80m tfc is trusted by NA statons...

F6KAR - WAEDC CW 2006

2006-08-15T16:23:00.000+02:00

WAE DX Contest, CW
Ops: F5VIH/SV3SJ, F6IFY, F6IRF
Station: F6KAR
Class: M/S HP
QTH: JN36AF

Band QSOs QTCs Mults
-------------------------
80: 86 2 21
40: 381 367 56
20: 390 714 64
15: 175 218 39
10: 52 24 19
-------------------------
Total: 1084 1325 496
Total Score = 1,194,864

High bands station:IC756 + Ten-tec Titan - Low bands station:IC756pro3 + Ten-Tec Titan
Ants: 80m: shunt-fed tower and sloper -40m: 40-2CD - 20-15-10: KT34 and 3el ECO - RX ants: Unterminated 100m beverages NE/SW and NW/SE, K9AY loop
Software: WIn-Test
The Weather has been extremely bad all weekend, with frequent showers and lowtemperatures (almost a CQWW-CW weather !)
With the Jura (8deg toward west horizon), our KT34 and a low 3el trap-yagi, wecould not expect to be really competitive on high bands, and this was confirmedby the difficulties we experienced in several pile-ups.
On low bands, it seems that we had a good signal but the WX strongly affected our receiving performances, especially on 80m.
Anyway, those details apart it has been a great weekend, without major technical problem, and we are more than happy with the score.
The conditions: Surprising! Based on the few days before, we did not expect 15mto open toward states, not to mention 10m. The strong multiple hops E's, really helped, resulting in 31 five-banders, 5 U.S call-areas on 10m and 7 on 15m.
The traffic: On a total of 44 DXCC entities worked, more than 2/3 of the QSO'swere achieved with NA. A few "interesting" entities were there. Just to mentiona few: 3W, 4K, 9K, 9M, 9V, A6, CN, FP, HP, VP9, P4, V31, VP8/h, VQ9...
The activity: Obviously being on the Eu-side and working only DX stations can't generate high hourly rates when you are at the bottom of the solar activity. Maybe the rules are still not yet understood, or is it the fact that north hemisphere summer does not stimulate HF contesters but getting new stations to work became quite a challenge on Sunday - we counted as much as 46mn between 2 consecutive QSO's... fortunately the QTC's were there ! On the other hand, it was not too hard to find a clean frequency...
The QTC's: The world may also be divided in 2 by the ones who deal with QTC'sand the ones who don't !!! (revised version of the famous Clint Eastwood sentence, in a Sergio Leone movie!) OK I understand the casual participant only responding to CQ's, but it is quite surprising to hear stations calling CQ-WAE, and refusing to send QTC's, even when the rate gets very low... Not to mention the "?" (meaning : what are you talking about ?) when you ask for QTC's ! A bit like running a KW in a QRP-contest !
Apologies to the stations we annoyed with repeated "QTC?", but for a EU competitor, the spontaneous offers are so rare, that there is no alternative strategy to aggressive search...
It has been a great pleasure for me for me to join the CERN RC(*) team - my first multi-op for quite some time -
Thanks to all for the QSO's and QTC's andto the DARC for organizing this nice event...
(*)CERN is the European Organization for Nuclear Research, the world's largest particle physics center. http://f6kar.web.cern.ch/f6kar/

CQ WPX RTTY 2006 RESULTS

2006-07-28T10:26:00.000+02:00

3rd world place, 1st EU and new EU record for TM6A in the SOAB LP category. See the contest story at: http://f6irf.blogspot.com/2006/02/tm6a-wpx-rtty-contest.html

3eme monde, et 1ere place EU avec un nouveau record d'Europe pour TM6A dans la catégorie SOAB LP. Voir le CR du contest à http://f6irf.blogspot.com/2006/02/tm6a-wpx-rtty-contest.html

Training material for the WAEDC CW

2006-07-27T09:24:00.000+02:00

ARRL RTTY ROUNDUP 2006 RESULTS

2006-06-05T08:52:00.000+02:00

The antennas used for this contest: Optibeam OB6-3M, SteppIR 2elements

PJ2T grabs the plaque for the DX SOAB LP category, but with the 2nd place, I established a new EU LP record. The contest story, and a few audio clips demonstrating the SO2R technique: http://f6irf.blogspot.com/2006/01/f6irf-arrl-rtty-roundup.html http://f6irf.blogspot.com/2006/01/rtty-so2r-audio-clips.html

ARRL RTTY 2006 results

PJ2T enlève la première place, pour la catégorie DX SOAB LP, mais avec la seconde place de la catégorie, j'établis un nouveau record Européen. Le contest-story et des clips audio du contest (demontrant la technique SO2R) sont la http://f6irf.blogspot.com/2006/01/f6irf-arrl-rtty-roundup.html http://f6irf.blogspot.com/2006/01/rtty-so2r-audio-clips.html

F6IRF: Rien de neuf... ou presque

2006-06-04T10:32:00.000+02:00

Bienvenue à Axel et Mael, déjà à l'entrainement avec Morse-Runner... La maman Suzy se porte bien, mais le père PM(HB9DTM/F6FNL) montre qqs signes de fatigue !
Welcome to Axel and Mael, already training at Morse-runner. The mother Suzy is OK, but the father PM(HB9DTM/F6FNL) looks tired.
F6IRF/CN2WW actuality is on http://cn2ww.blogspot.com/ WPX and peri-contest activity... you'll know everything about my last trip to Morocco...
Kevin en 1988 avec mon transceiver fabrication maison...
Kevin in 1988, with my homebrew transceiver...
Toute l'actualité du moment se trouve sur : http://cn2ww.blogspot.com/ WPX-contest et peri-contest activité, vous saurez tout sur mon dernier séjour au Maroc.

CN2WW soon on the air

2006-05-15T09:16:00.000+02:00

I will be active starting saturday 20, until wednesday 24 from Dar-Bouazza (nr Casablanca) from CN2DX location.
Depending on the condx, I may take part in the "king of spain" HF CW contest, or focus on 6m band. Outside contest, I'll focus on WARC bands.
Will then move to Casablanca, and then to CN8SG's place in Kenitra from where I'll be active for the CQ WPX contest.
Conventional QSL via EA7FTR, electronic confirmation via LOTW. See you on the bands.

Morse Runner training for the WPX

2006-05-08T15:04:00.000+02:00

More runner is a CW-Contest training software developped by VE3NEA. It is probably the best tool ever developped to improve the CW-op contest skills...

Morse-runner demo by F6IRF

Above you can see the log, and the software settings for the 5mn audio-clip. Net-rate is 240 QSO/Hour. You can check the morse-runner toplist on http://www.dxatlas.com/MorseRunner/MrScore.asp . My best score on one hour is currently with CN2WW callsign (208 QSO's), but feel that I still have some progression margin...

F6IRF - 1ST WORLD RTTY CONTEST OPERATOR

2006-05-02T10:17:00.000+02:00

As shown by main toplists, F6IRF callsign still appears as World number one !
This is the result of my 2005 activity... this will change soon as, for 2006 I am more focusing on CW contesting and overseas activity.

http://home.arcor.de/waldemar.kebsch/

http://www.rtty-contest-scene.com/index1.html

CN2WW in the WPX CW-contest

2006-04-19T11:46:00.000+02:00

Got the confirmation from the ARRAM that the callsign CN2WW has been reallocated to me by the ANRT. If everything goes as expected, I will operate in SOAB from CN8SG station in Kenitra.
http://radioamateurs.he-arc.ch/cn2dx/articles/cn8sg/

see also: CN2WW UBN's on http://cn2ww.blogspot.com/

4U1ITU - Russian DX Contest

2006-03-21T10:35:00.000+01:00

Call: 4U1ITU
Operator(s):
F6IRF, HB9DTM, SV3SJ
Station: 4U1ITU
Class: M/S HP
QTH: Geneva
Operating Time (hrs): 24

Band CW Qs Ph Qs Countries Oblasts
----------------------------------------
160: 99 3 35 22
80: 341 71 55 46
40: 769 50 69 61
20: 556 284 65 68
15: 23 83 39 32
10: 1 0 1 0
----------------------------------------
Total: 1789 491 264 229 Total Score = 7,034,124
total 2280 QSO's / 14268pts / 493 mults

RIG: IC765 - IC756proIII - Alpha91B - Tentec Titan
ANT: FB53, 4EL20(fixed NE), 40-2CD, dipoles 80/160
Soft: N1MM Logger V6.2.15

the team: Nico SV3SJ, Pat F6IRF, PM HB9DTM

Preliminary:
First M/S operation from the ITU-RC for quite some time. The initial plan was to get UR5FAV and UX0FF to join the IARC-team for a MO2T, but the Swiss authorities in Kiev did not like our idea. So we had to improvise a last minute "B-plan".
After the loss of one tower and the 15/10m monobanders last year, we had to re-install the low band dipoles and put the 20m monobander back to service, which we did on Friday afternoon. We thought we may had time for setting up a L for 80m, and a K9AY-loop, but we ended up "short of time". With the 20m monobander only 3m above the terrasse, the low band dipoles at 90 degres from Russia (the historical "Varembe" building is oriented NE/SW) and if you add the known "noisy urban environment" and the modest antennas surrounded by high buildings, you have an overview of what makes contesting from 4U1ITU a special challenge.
So our main objective was to get the 4U1I multiplier back to the international contest scene, rather than becoming a serious challenger to UP5G !

Nico thinking: If only we could put the antennas on top of the ITU tower... (west horizon)

The contest:
No need to say that the high-band conditions have been bad. 20m closed early,and re-opened only three hours before the contest end. 15m remained absolutelydead until the last hour, and did not allow a single UA station to be logged onD2. We took a difficult start with some keying problems due to RF-feedback, so we changed the run to SSB for the time needed to solve the problem: It justconfirmed that in spite of Nico's skills and efforts, our signal was not strongenough for SSB to produce any decent rate. 15m died during the third hour,quickly followed by 20, so we ended up running on 40 far earlier than planned.The rate dropped below 100 around 22z, when 40m became unproductive. The Alpha91producing only heat and smoke on 80 and 160, we moreless limited the trafic to 1station during the night.Back to "historic contesting age" on 160, where all CW QSO's had to be done fromthe paddles, due to RF affecting the computer...Finaly we spent the 2 last hours on 20m/SSB, and the log being almost virgin onthis band/mode we brought the rate above 100.

No major problem was experienced with N1MM-logger; just that it was not possibleto remove the station "interlock"... here also we had to use the paddles...
In general we could have done a bit better with a more careful preparation, but we really had a good time, which remains the essential at the end !
A special tribute has to be given to the RDXC commitee for the rules and the organization, and to the Russian hams stations for the activity and the quality of their trafic...

PM in action and the South-East horizon !

A buro card will be sent to all stations in the log (your card is not required),and all QSO's will be uploaded soon to LOTW. Should you need a direct card,please only via IARC, P.O.Box 6, CH-1211 Geneva 20, Switzerland

Country and oblasts summaries at http://lists.contesting.com/archives//html/3830/2006-03/msg00953.html

More pictures soon on http://life.itu.int/radioclub/index.html

the 40-2CD, the 80m SSB dipole and the 20m monobander (NE horizon)

And what about SSB-Contests ?

2006-03-02T16:36:00.000+01:00

One of the reason I am rarely active in SSB, is that I never managed to understand how to use the SSB accessories...
"Heil sound" copyright HB9DTM

The "LID-price" is awarded to UW8M

2006-02-24T10:59:00.000+01:00

UW8M alias UR5MID
A nice QSL, but a dirty "on the air" behavior...

This is an obvious example of unfair behavior in a contest. Take a frequency randomly, put your auto-CQ for 5minutes, go for a coffee and you have good chances for the frequency to be yours when back...

ARRL-DX CW AUDIO-CLIP

As shown, by the log, I was on the frequency for some time, and it was working fine....

TM6A ARRL-DX CONTEST

2006-02-21T14:23:00.000+01:00

(click to enlarge)
40m has been by far the best band with 500 QSO's logged in only 6 hours - hald of them during the 2 last hours

Call: TM6A
Operator(s): F6IRF
Station: F6IRF
Class: SOAB(A) HP
QTH: JN35AU
Operating Time (hrs): 15

Band QSOs Mults
-------------------
40: 501 51
20: 334 57
15: 91 26
-------------------
Total: 926 134 Total Score = 372,252
rig: IC756pro2 +homebrew 4CX250 PA 500W
ant : 2elts wire-yagi / Optibeam OB6-3M

Part-time/casual effort; Started the contest on saturday evening, after a verybusy and tiring saturday. The main objective was to test the addition of a passive reflector on my 40m dipole (see below), but I quickly gave up due to high local noise (rain on 380kV power line) and ended-up in bed earlier than planned... In fact the real fun started sunday evening, when the rain finaly stopped: 230 QSO's logged on 40m during the 2 last hours (best 30mn @150 ), confirmed that the antenna was working fine... a 2 hours great pile-up which I'll keep in mind(probably the best ever, from my modest domestic station !)
Finaly 40m has been by far the best band with 500 QSO's logged in only 6hours... (for sure that's promising for future contests...)
Superb conditions also on 20m late sunday evening; but was to impatient to test the 40m antenna (same for 80m !) ... Finaly and in spite of the limited time spent on the air all US-states have been worked except SD. A pity the weather did not help, but to be honnest I had been too lucky for many weekends in 2005 !

A low-cost 2 elements for 40m

2006-02-20T14:42:00.000+01:00

Objectives: - Improve reception toward NA, by attenuating EU-signals
- Provide some substantial gain over my usual dipole (3.5~4dB)
- easy to erect/remove

Playing with MMANA and NEC2 I discovered that placing a passive reflector some 8m (0.2 wl) behind my standard inverted V-dipole, I could get near to 4dB gain, while maintaining an acceptable SWR in the 50 ohms line (typ 1.7).
I also discovered that the passive reflector could be noticeably lower than the dipole, just sacrifying a few tenth's of DB.

Above: the concept, and the simulated performances (in red) compaired to a dipole at the same height (in blue) and to a 4 radials GP at 10m (black)

Below: the practical realisation with the dipole at 19m (7m above the tribander), and the passive reflector with the appex at 15m. The reflector can easily be folded along the fiberglass mast to restore the bidirectional pattern of the dipole... In the background, the 380kV power-line !

TM6A WPX-RTTY CONTEST

2006-02-13T15:51:00.000+01:00

Call: TM6A
Operator(s): F6IRF
Station: F6IRF
Class: SOAB LP
QTH: JN35
Operating Time (hrs): 30
Radios: SO2R

Band QSOs Pts
-----------------
80: 432 1806
40: 487 2184
20: 430 1097
15: 70 183
10:
-----------------
Total: 1419 5270 Prefixes = 528 Total Score = 2,782,560

Station: my usual SO2R minima-setup @150W
http://f6irf.blogspot.com/2005/08/so2r-minimal-setup.html
A fantastic contest despite poor conditions. Tremendous participation,
I had never seen the 20/40/80 digital segments extending that far away
from the theoretical limits...
This year the local WX was perfect and allowed me to put my last year
"low bands" strategy in practice...
http://lists.contesting.com/archives//html/3830/2005-02/msg00679.html
The only disapointment comes from the limited number of prefixes,
(only +4 compaired to last year - congrats to UT9FJ for the 575!), but with
a 30% improvement over my last year score the claimed is above the current
EU-record for the category

(click to enlarge)- those 2 graphs show the top-ten qso and prefixes providers.
( http://rttycontesting.com/records/cqwpxrtty.html )

N1MM-LOGGER is getting better and better, and performed near to the
perfection - once again thanks/congrats to the programmers team.
Country stats can be seen at
http://lists.contesting.com/archives//html/3830/2006-02/msg00548.html

Thanks to all for the QSO's - E-confirmations soon on LOTW
Pat (not Serge!)
F6IRF
WPX RTTY - 2006-02-11 0000Z to 2006-02-13 0000Z - 1429 QSOs
TM6A - Off Times >= 60 Minutes
Total Time Off 18.03 hours
Total Time On 29.97 hours

As shown on those graphs, I took most of my off-time during the day. I also spent quite some time on 40 during the day, and limited 15m mostly to the JA window.
About the strategy: It may not be obvious for everybody, but the WPX is one of the most interesting contest on a strategic point of view. What make it so interesting is the fact that SO may only operate 30 of 48 hours, that QSO-points are multiplied by 2 on 40 and 80, and mults only counted once.

As shown on the various graphs above, my strategy was deliberatly "priority to low bands", with the majority of off-time taken during daytime. The consequence of this strategy is a relatively low number of multipliers per QSO's versus a high number of points/qso.

This graph shows that various strategies may provide close results. Obviously the situation is quite different seen from Israel or USA...

Will be TM6A in WPX-tty and ARRL-DX-CW

2006-02-09T12:10:00.000+01:00

Received TM6A callsign for period 10/02/06 to 23/02/06.

At h-36 from WPX start the conditions do not seem very promising...
Only 2 small sunspots are visible on the solar dish (SSN 12) while the Ionosonde NWRA SSNe indicate a value of 20
Anyway... not much to expect from 15 and 10m...