Topband: Magnetic Loop Height Question

[Richard (Rick) Karlquist]

On 10/25/2021 8:32 AM, W7TMT - Patrick wrote:
> I'm looking to improve my receive situation on 160. Given the numerous limitations to my location it appears my best chance of seeing any improvement might be a small loop. All of the designs specify a minimum height of above ground. The DXE version suggests 5 foot as a minimum and other designs are similar. Any thoughts on what that number would be if we are talking about super conductive ground below it, in this case saltwater? Any other considerations with a loop over seawater?
> 
> Thanks for your time.
> 
> 73, Patrick, W7TMT

Hi Patrick:  You had a great signal during the recent Stew Perry;
love that salt water.

Since you asked about loops, I will plug mine:

http://n6rk.com/loopantennas/NCJ_loop_antenna_N6RK.pdf

All this loop (or any other one) does is allow you to null out
a single noise source.  If your noise problem is such that
you have a dominant noise source, they can be useful.

I don't know where you got that there is a minimum
height above ground.  W3LPL actually says NOT to raise
up the loop, for complicated reasons I won't go into here.
I don't even think being over salt water matters.  A loop
is basically a phased pair of verticals; verticals love
salt water.

For receiving, the trouble with salt water is similar to
the trouble with my high conductivity clay:  it propagates
all local noise VERY well.  What has worked here is to
put up a low dipole to reject some of the vertically
polarized noise.  Maybe two (choose one) of them at right angles.
They do unfortunately receive vertical noise off the
ends.

BTW, a Beverage is a non-starter over salt water, as
is well known.

Another thing that helps is having a good SDR like my
Flex 6700 with very narrow (down to 50 Hz) non ringing
CW filtering.

Hope to work you again in the big Stew!

73
Rick N6RK