I made this thing a couple of years ago and didn't seem to have a lot of luck with it. I think it might have been because it was too close to the house, which has aluminum siding. It might have also been the fact that it was only about 2 feet off the ground. In any case, I put it behind the shed in the back yard and left it there.
Well, after spending the better part of 2 months adding to the radial field of the 160m antenna, I decided to resurrect the old coax loop. This time, I tried to find a better place for it. That place wound up being mounted to the back of the same shed I had left it behind to rot.
Now, I only got it mounted yesterday (Thursday), and only played with it for about 2 hours late last night. So far, I've got to say I'm having better luck this time around. Yes, without an external preamp the signals are down quite a bit, but the S/N ratio appears to be much better with several of the signals I found. In a couple of cases, SSB signals that were barely higher than my s7 noise level (and were a major problem to discern at all) suddenly became perfectly copyable against an s3 noise level. Of course, having it on a cheap rotator to null or peak signals doesn't hurt, either.