In rec.radio.amateur.antenna Spike wrote:
On 03/12/2015 12:45, Brian Howie wrote:
In message , Spike
writes

Note for Brian Howie: the study encompasses 472 kHz, and it should be
noted that below 1MHz the soil electromagnetic parameters diverge
significantly from HF values. This implies that a different approach
is needed, and one of the articles looks at this - you might find
this of interest.

Thanks I've had a look at them . If I ever get round to transmitting
there, I'll need a lot of earth.

I guess it will need a lot of planning! And wire...

I'm still using my 5 foot loop for receive, but it's now series tuned,
rather than parallel with a coupling loop and seems to work a bit better.

Do you find the S/N is improved with a loop? Have you thought of trying
a shielded loop?

By coincidence my morning training run took me near the EDN NDB

http://www.b-howie.demon.co.uk/lfbcon.htm

It's a top loaded vertical, but looking over the fence, I could see a
lot green earth wire radials on the surface. It's possible there are
buried ones too , but there are only about 6 and they can't be more than
15ft long,

For the beacon to be of maximum use, they'll need a good sky-wave
signal; it sounds like the visible radials are there to provide a DC
path to earth probably in association with a ground spike, rather than
for getting the main lobe lowered.

Sky wave propagation doesn't happen at those frequencies for all practical
purposes.

Sky wave propagation was discovered when amateurs started using frequencies
greater than 200 meters.



--
Jim Pennino