[Elecraft] A small FD experience

[Ron D'Eau Claire]

Tests run in 1965 by W0YBF with an underground doublet (it was buried about
2 feet below the surface of the soil but the wire was insulated from the
surrounding earth by putting it inside a plastic pipe) showed that it was
about 18 dB below an elevated dipole - about 3 "S-Units". Perhaps a wire ON
the ground would be a bit better, especially if it was insulated.

Still 3 S-units isn't bad for a completely invisible antenna that, by
definition, can't blow down in a storm<G>.  And it picks up very little
local QRN on receive. Many ops looking for a low QRN antenna in a noisy
location simply throw a wire on the ground and get far better results than
with a resonant wire up in the air. 

Underground and on-the-ground antennas date waaaaay back. There was on in
the RSGB "T & R Bulletin" from February 1927 by C.H. Taggett, G6PG, who used
a 60-foot rubber insulated wire buried 2-1/2 feet down. That one was end fed
with the "feeder" passing through a length or rubber hose to the
pipe-enclosed antenna. G6PG ran 8 watts into the antenna on 150 meters, 90
meters and 45 meters back in the 20's with contacts ranging out to about
1000 miles. Interestingly, in spite of the fact that the antenna was only 60
feet long, he found it to be very directional with most contacts within an
angle of 30-degrees from the far end. 

My references mention underground antenna experiments going back to 1912. 

Later center-fed versions, such as W0YBF's, center-fed the antenna with a
matching network in a plastic garbage can underground with the lid
accessible from above so it could be opened for adjustments. 

I've used an on-the-ground antenna too, and gotten out with it... At least
until I went outside to investigate why my ATU settings had changed so much
and noted that it had fallen down from its supports<G>.

Ron AC7AC

 

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of N2EY at aol.com
Sent: Monday, June 28, 2004 11:20 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] A small FD experience


In a message dated 6/28/2004 1:33:05 PM Eastern Daylight Time,
n6kr at elecraft.com writes:

> I double-dare you to model this antenna in EZ-NEC, > Tom  ;)...


73 de Jim, N2EY