Re: Ground wave transmission, was G-line

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Steve, all,

On 17 Sep 2005, at 11:11, Tesla list wrote:

> Original poster: Steve Conner <steve@xxxxxxxxxxxx>
>
>
> >Ground wave transmission, Tx =  2 stakes in the ground 1/4 wave
> >spaces
>
> This I do believe. I have a couple of cookbooks with plans for
> various ham radio antennas, and there are a few underground antennas
> in there :-o
>
> The construction article mentioned that they had tested an
> underground half-wave dipole (buried 8 inches down) alongside an
> ordinary half-wave dipole elevated 0.3 wavelength above ground. The
> underground antenna was 16dB worse. But that is still quite usable
> considering that the underground placement seems to block out
> interference so you can use more receiver gain.
>
> 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.
>
>
> Questions to ponder:
>
> If you dug a huge pit, and buried a HF beam antenna firing vertically
> up to the sky, would you get ground waves or air waves? :-) In the
> light of the recent thread on A&E TV, maybe we could bury some lawyers
> with field-strength meters down there too, and ask them to report back
> to us. :-))
>
> Would underground antennas still look 16dB worse, if both ends of the
> link were using one? Or is the 16dB loss caused by trying to receive
> ground waves with an airborne antenna?
>
>
> Source: "Practical Wire Antennas", Heys, J.D., Radio Society of Great
> Britain, 1989, pp. 79-80
>
> Steve Conner
> http://www.scopeboy.com/

A few years ago I buried two sets of tangled copper pipes about 30
feet apart on my section and built an amplifier to monitor the
differential voltages. There were lots of interesting signals
appearing on the scope. One of the most prominent was a squarewave
with a frequency of about 0.5Hz. Fascinating is the word.

Malcolm