RadioBanter - MFJ 1786 High Q Loop

Steve wrote in news:a35c927b-be20-411c-a4cf-
:

I've heard good things about these loops, but wonder what they're like
on receive. Can anyone comment?

Thanks,

Steve

Hi Steve:

I had one in the past. As in all antennas they receive like they transmit.
The performance of the antenna varies with the frequency. At 10MHz it’s
very narrow and its gain is a good bit less than a dipole. At 28MHz it’s
very similar to a dipole and in the middle of its range slightly less than
a dipole.
Like all antennas the performance varies with how high it’s above the
ground and with the compact loop there is one other slight problem. When
the antenna is mounted horizontally it must be at least 20’ to 30’ above
the ground. Mounted horizontally it is Omni directional. If it isn’t
mounted that high it must be used with the loop vertical. In this case it
can be as low as 3’ and still work but it will be directional. It will have
nulls at right angles to the loop and have its best response in the plane
of the loop. In mine I could get a very good SWR over the whole range but
at 10MHz the 2:1 SWR range was about 5KHz and became wider as I went up in
frequency to about 100KHz at 28MHz. This SWR bandwidth also applied to the
receive signal levels. If I tuned my receiver away from the low SWR point
the signal levels dropped by large amount. This is a very usable antenna if
you are one who sets in a small range of frequencies, like maybe a net
operation, it is a frustrating antenna if you like to tune around a great
deal. There is one maybe useful feature of the narrow tuning. It may be a
quieter antenna just because it acts as a high Q band pass filter in front
of radio and may help on a noisy band with a not so good radio.

John Passaneau W3JXP