Message-ID: <004201c3785b$e01167e0$3704210a@Hugh>
From: "Hugh M0WYE" <m0wye@thersgb.net>
To: rsgb_lf_group@blacksheep.org
References: <3F604383.4358.5B6012@localhost> <001e01c37852$deaf7d00$6507a8c0@Main>
Date: Thu, 11 Sep 2003 12:57:20 +0100
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Subject: LF: Re: Re: re EWE aerials
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Alan, et Group,
The Services Textbook of Radio (1958) Volume 5, (page 336) says that "a
Beverage, or wave aerial, is a straight wire several wavelengths long,
usually carried by insulators on telephone poles at about 30 feet above the
ground..."
Further on it says "Such aerials should be at least one wavelength long, so
that for the very low frequencies involved, several miles of line are
required. They are therefore only suitable when a large area of poor
conductivity ground is available."
The method of operation proposed is that there is a degree of tilt of (1 to
4 degrees depending on ground type) to the wavefront passing over ground so
that there is a horisontal component which will produce an induced emf in
the wire.
If I read the explanation right, the degree of tilt is greater over poor
conductivity ground, and this gives 4 times as much emf as over good ground.

I don't see that 300m of wire can really be referred to as a Beverage,
representing only about 1/7th of a wavelength.

73
Hugh M0WYE

----- Original Message -----
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, September 11, 2003 11:16 AM
Subject: LF: Re: re EWE aerials


> 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
> > ==========
> >
> >
>
>
>