Re: Ground wave transmission, was G-line

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: robert heidlebaugh <rheidlebaugh@xxxxxxxxxxxxxx>

A burried dipole or coil antenna is not the same as two stakes in the
ground. An insulated antenna burried above the water table projects an
immage antenna the same distance above the ground as the antenna is burried
down so part of the power is an air wave and part is a ground wave so the
total power at the reciever is lower than a above ground antenna. This was
tested for NASA to develop a hardened antenna system for missile sites. In
Majave desert dipole antenna were burried  in the desert beyond normal TV
reception range only 4 ft down and were able to recieve clear TV signals.
The antenna were lengths of net fence wire one role long each way in a
trench made with a cat tractor. Yagi and 1 meter ferrite antenna were also
tested  in bore holes, with good results. The fence wire was large an worked
best. Tests were done in 1962.
     Robert   H
--


> From: "Tesla list" <tesla@xxxxxxxxxx>
> Date: Sat, 17 Sep 2005 14:52:22 -0600
> To: tesla@xxxxxxxxxx
> Subject: Re: Ground wave transmission, was G-line
> Resent-From: tesla@xxxxxxxxxx
> Resent-Date: Sat, 17 Sep 2005 14:54:24 -0600 (MDT)
>
> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
>
> "This is not quite the same as Robert's setup where he drove stakes
> into the ground and passed the RF current through the ground itself.
> These antenna systems used a 1/2 wave wire dipole buried in the
> ground and presumably excited waves in the ground through induction.
> But I reckon the effect would be pretty much identical.
>
> The only thing I'm not sure about is how you can develop waves in the
> ground alone. These underground antennas were tested by talking to
> other hams who were using normal above-ground antennas. My reading of
> the situation is that the ground-air interface "leaks" so that you
> produce waves both in the air and the ground, no matter whether you
> use a buried antenna or an elevated one. But that is just my opinion
> and up for debate."
>
> An "underground antenna" will work provided the ground conductivity
> isn't too high.  In the old days people did a lot of work (or at least
> wrote a lot of articles) on the merits of underground antennas for nose
> rejection but I suspect the observations were erroneous and that the
> signal to external noise ratio was at best the same as an above ground
> antenna, and probably worse.
>
> Ed
>
>