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

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...