Pete W2PM wrote on the 9th May, "Andy. Again, it's the laws of physics which apply. The mag loop can only be sensitive go the magnetic field and less so to the E field only if it is very very close to noise source. That's just the way Nature works. The sn improvement is mostly from the very deep and sharp null. You point the null to the noise. I have seen 20 over S 9 noise go to s1 with cheaply made mag loops. That's very good. Problem is in an urban and suburban area there may be many noise noises so eliminating one may not help. But it may. Even so the mag loop is sensitive to all signals local or distance in a vertical donut shape. Most DX at 160 and even higher bands comes in at low angles and most QRN from lightning etc comes in high angle. The only way to get meaningful and useful performance in a rx antenna is for directivity in the right vertical and hortizontal fields. This is all for DX performance. If you have nasty local crud noise coming from a certain area and it creates s9 plus hash in your receiver and all you want to work is domestic, the loop is fine. And in some conditions its ok DX. I worked my first VK with a mag loop. But there's no magical properties for it and if you want predictable DX performance it's fine as a single tool to have but I'd not spend much money or other resources on it."
Pete, What I have found is that there is still a significant E Field noise reduction even when the loop is not nulling the noise. This is not just my observation. There are approx. 5000 ALA1530s in current use in the US, Europe and Japan. The feedback I have from users experiencing high levels of local noise is that in most cases the loop affords a noticeable improvement in the s/n. Your point in increasing the antenna directivity for Dxing is quite valid if the local noise is low. Here I use a 2 x K9AYs spaced 40m apart as a 200kHz to 2MHz phased array; the antennas are run in anti-phase with a varible delayline phasing controller. Interestingly with this array; if I replace the K9AYs with 2 large loops I can get up to a 20dB reduction in the local noise. However, the reduction in array directivity does make this a non preferred option. 73 Andrew _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
