I particularly enjoyed the user comment about the VHF loop. It never fails to amaze me what a great tool it is and how few hams or others ever consider it. Like the man said, it is a losser at any frequency except at self-resonance, but it does such a beautiful job of eliminating half the reflections and the null (or minimum) is so sharp.

The "inventor" of the loop is obscure. But I know that very large rotatable loops were used in WW1, searching for LF German ship transmitters off the East Coast of the U.S. The loop is really a coil, if you think about it. Many loops are made up of multiple turns for frequencies in the Low and Medium frequency spectrum, shunted with a variable capacitor to permit a range of frequencies. Because of resonance, the loop becomes smaller, even down to a single turn, as the frequency increases. For practical purposes, loops aren't used much above 1 GHz, although there are a few loop/yagi antennas above the 1 GHz range, but there they are used in the "maximum" full-wave mode for gain. The Faraday shield on this VHF loop (and the UHF loop) blocks the electric field, allowing the two loops to work only on the magnetic field, thus reducing reflections.

As I think I told you, I built my first loop for the old 5 meter band back in 1939. I found that with careful tuning with lecher wires (remember them?) to get a resonant loop, I could get a really good figure 8 antenna radiation pattern. Also, we had a bootlegger in my little (then) home town of Anaheim CA, and that's when I discovered its DF capabilities. Found him, too. Turned out to be a high-school classmate that couldn't pass the exam!

For users of my K95-103 handheld DF system, I suggest that for initial acquisition of a signal, when it is too weak to give a S-meter reading with the loop, to use USB, LSB, or CW mode which will give a beat note which makes it very easy to take a bearing aurally.

I've been using loops ever since, throughout both my FCC, FAA and Consulting careers. Both FCC and FAA use loops for DFing, particularly in near the source. The difference is that I've never had any that are so professionally crafted to my specs. I've sold over 200 of the HH DFs to FAA, FCC, Army, Canada, etc., and even one to a Professor of Electrical Engineering at the University of Oregon. And everyone speaks to the professional quality of all the antennas. You are famous in your own right.

Thanks again for giving me such quality products for my systems. I feel privileged to have had a small part in your development and production of them.

You can excerpt any part of this for your user comments if you wish, since it's truthful. :-)

73,

John P. Kemper, P.E. W6JN