I will second Bruce's comments. Re-radiated noise is almost exactly what you are describing.
I started using terminated loops around 2000 and even though everyone said that the transmit antennas needed to be detuned when receiving, I was stubborn and didn't follow the advice immediately. The loops were noisy and lacked directivity. I caved and added a circuit to detune on receive and the loops got quiet and were really quite directive compared to what they had been. As a side note - I had need to install a low 80m dipole last summer temporarily. I did not provide a means to detune it - I never thought about it really as it was completely off my radar. It was not until I tried to use the RX loops on 80 that I realized what I had done (or note done as the case was). Anyway, that dipole came down pretty quickly and the loops began behaving normally again.. Any RX antenna is going to behave similarly - shielded loop, K9AY loop, beverage, it does not matter - if you don't detune the TX antenna or get the RX antenna a long way away from that TX antenna. 73 and good luck, John KB5NJD.. ________________________________ From: Bruce <[email protected]> To: [email protected] Sent: Sat, June 16, 2012 11:58:36 AM Subject: Topband: Receiving loops Tim, Your receiving antennas may be picking up re-radiation, of noise and signals, from the transmitting antenna. Try detuning the TX antenna while receiving. (If best receiving on the loop is with the null toward the TX antenna, it is a indication.) 73 Bruce-K1FZ _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
