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.


--
Spike

"Crime butchers innocence to secure a throne, and innocence struggles
with all its might against the attempts of crime"

- Maximilien Robespierre