Message-ID: <005e01bebc89$a8b18420$d197b38f@w8k3f0>
From: "Dick Rollema" <d.w.rollema@gironet.nl>
To: rsgb_lf_group@blacksheep.org
Subject: LF: Re: Antennas
Date: Tue, 22 Jun 1999 10:30:46 +0200
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G3XDV de PA0SE

Mike,

You wrote:

One a similar topic, what influences the capacitance of a multi-wire
top section? Is it simply wire diameter so a thick wire has more
capacitance than a thin wire? What about multiple parallel wires -
these are often suggested to be a metre or so apart - why? If the
distance makes a difference, do I assume that the further apart
they are the better the effect, and if so why is this?

Also, if I run three top wires in parallel, should I join them at the far
end? Or perhaps I could join them so they make a single zig-zag
wire down the garden, back again and down again.

The antenna is getting better all the time, but I am sure there's
more progress to be made. Does anyone have some practical
experience to pass on?

My reply is:

I cannot provide practical experience. Computer programmes for antenna
simulation are no help either as dimensions  of the aerial are are too
small, expressed in wavelength.

But I found some useful information in a 1925 book called ELECTRICAL
ENGINEERS DATA BOOK, VOLUME THREE, RADIO ENGINEERING.

It has a chapter on "Capacity of Aerials" and I think it answers most, if
not all, of your questions.

I have made a photocopy of the chapter and will put it into the mail today.
It goes to  your address at RSGB as I am not sure of your home postal
address. An attempt to look at your homepage failed; system overloaded?

73,

Dick, PA0SE
JO22GD
D.W. Rollema
V.d. Marckstraat 5
2352 RA Leiderdorp
The Netherlands
Tel. +31 71 589 27 34
E-mail: d.w.rollema@gironet.nl
or
pa0se@amsat.org