Message-ID: <001e01c37852$deaf7d00$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <3F604383.4358.5B6012@localhost>
Date: Thu, 11 Sep 2003 11:16:01 +0100
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Subject: LF: Re: re EWE aerials
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Hi Mike, that is an interesting philosophical / technical point....what is
the length of a Beverage ?? they obviously work better if they are longer,
and the aerial has more "coupling" to the wave front....maybe more time to
integrate the energy in the wavefront.....but does that make a short (less
than a wavelength) travelling-wave aerial not a Beverage?? I tried to relate
these type of aerials to the terminated directional coupler loops used in
coax and waveguide....but the "direction" seemed to be the wrong way
round.....I never quite understood why.

This leads on to the oft quoted ground aerials....where an insulated wire is
laid along the ground or buried in a shallow trench. Reading the history and
comments by Beverage would suggest that the reason for using this
configuration was the "low-pass" effect it produced. In the days when
selectivity was relatively poor, and there was a lot of noise at higher
frequencies, the ground aerial did not respond to the higher frequencies.
Then being generally laid on poor ground that VLF signals could easily
penetrate, even a zero altitude aerial had some "effective height". This
suggests that the aerial would be "relatively poor" at 136kHz, though I
certainly pick up a substantial signal on my counterpoise wire when I use it
as an aerial. It is obviously a lot cheaper to lay a wire on the ground that
support it for several kilometres on poles. No doubt this was an important
factor in the early competitive period of radio.

Cheers de Alan G3NYK
alan.melia@btinternet.com

----- Original Message -----
From: "Mike Dennison" <mike.dennison@ntlworld.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: 11 September 2003 09:42
Subject: LF: re EWE aerials


> On 10 Sep 2003 at 21:11, Alan Melia wrote:
>
> > Finbar has also had reasonable success
> > with a form of Beverage (no, not Jameson's) 900 feet long run about 5
foot
> > in the air down the beach. It only worked in some directions, which is
odd
> > because a Beverage is not supposed to work at all over good ground (like
> > sea-water).
>
> Ah, but at less than one-sixth of a -wavelength long it wasn't really a
Beverage, was it?
>
> Mike, G3XDV
> ==========
>
>