Receive Arrays for small footprints, combat QRM etc.

 LZ1AQ - AAA-1C

It must be now close to  years since I have been playing with different way to improve my RX capabilities at mmy QTH, which as you all know by now is of very small footprint, and all TX antennas are packed up.On the positive note, I would like to say that YES, it is possible, BUT you do need to take care of multiply things before you can seriously improve your SNR.. (I am talking about 160, 80 and 40).

Some would argue that TX or TRX antenna is all you need, which might be true if you run large YAGIs or directional arrays, in super quiet location, but for those of us who happen to live in urban areas with neighbors and houses, SM PSUs , PCs large TVs etc., man made noise is killing the RX and you fight every dB you can. And I want to stress this out, every dB, or even half of dB counts! Yes, SNR 0dB means noise, SNR 1.5dB means CW QSO with 349-449 RST.

I started with simple K9AY Loop directed to NW to SP USA but quickly moved away, given that easier solution is to use small RX Loops. I came across LZ1AQ system online while looking at various options. After receiving the AAA-1C, I made two dirty cheap loops from 2mm copper wire and then from RG6 coax cable. Results were good. I could hear much better on 80m for both local chat/NVIS but also noise dropped and I could listen to MW/LW broadcast, NDB's etc. I still could not work real DX as weak signals were just not strong. 

I extended the loops to 1.8m diameter as I am not interested in anything above 40m band really. I mean, I did find out that loop mode works well on 15m, 12m etc.and I hear better than on rotary dipole, but I was mostly after low bands. 

I purchased three units and since the phasing box was no longer sold, I decided to try build something myself. I instelled the three loop system first as L-shaped. So I could use external phasing via software or box (NCC-2, QRM Eliminator etc.) to make the array steerable. Results were amazing. I settled with 3 element, in-line array, with spacing of 10m between the loops. Antenna-wise I was using 1.8m loops, orthogonal, with one loop at top and on at bottom, 90deg and I could select A/B or A+B and dipole mode. I could also select NW / SE using 0,90,180deg phasing for each element, and I made sure I ran same length of CAT5e to each loop system. 

I remember clearly the day I worked ZL1 on 160m, which I could not hear at all on TX vertical. VK9DX was also worked using the loop array, but in Broadside phasing! 

My biggest surprise came in the morning when I worked 3Y0K on 160m CW. I had dedicated beverage southwards, 225m long, just 15cm off the ground. When I finished QSO I decided to listen, and try loops. To my amazement, I could hear 3Y0K on SINGLE loop (I have N/S  and E/W orientation of individual loops) and yes, beverage was 579 and single loop was 449 kind of signal, BUT it is amazing, the Bouvet would be workable using just TX Vertical, and single AAA-1C! 

I since then moved to dedicated phased beverage arrays, as I enjoy working US West Coast on 80/40 and nothing beats pair of 1200ft / 330m long beverages (staggered, end-fire) as I need to get rid of noise from the village, but I never took the LZ1AQ system down. Even though I burned few since my TX Array is just way too close for comfort, and yes, I NEED to detune, or float the TX antennas, when I Receive. Quick test showed that listening to DX, when I re-connect or disable de-tune of the 80m TX Array, my signal to noise drops and noise increases by 10dB or so, just by TX Array re-radiating noise. It also completely screw up the pattern.

Signle loop , so simple AAA1C system is sufficient enough if you are looking for low bands weak signal work. Play by the book, read the manuals and follow up some principles noted here. You wont be dissapointed!

73 Jiri