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G0FTD > WANTED 22.09.04 07:24l 30 Lines 979 Bytes #999 (0) @ WW
BID : ED6998G0FTD
Read: GUEST
Subj: Re: 70MHz Horizontal Mobile Ant?
Path: DB0FHN<DB0MRW<OK0PKL<OK0PPL<DB0RES<ON0AR<GB7CIP<GB7SXE
Sent: 040921/1714Z @:GB7SXE.#38.GBR.EU #:5937 [Hastings] FBB7.00i $:ED6998G0FTD
From: G0FTD@GB7SXE.#38.GBR.EU
To : WANTED@WW
PA2RHB wrote:-
>> A 'Halo' for 4 Metre is a bit big and may get
>> caught up in garage, car-port, or low flying objects! We used them on
>> 2 metre AM mobile, but that would be about the limit for convenience.
>
> It was the smallest I could think of. The diameter would be under 70 cms,
> much less than the width of the car roof. You could mount it lower (in
> terms of wavelength) than you ordinarily would a 2 meter version.
> For any horizontal 70 MHz antenna over a ground plane, 30cm seems to be a
> practical minimum, otherwise you would get too little lower angle
> radiation.
30cm over a car body, low angle radiation ?
You'll get most of the radiation going upwards, and tailing over at
about 60 at the -3db point.
Very good for working satellites above your head ;-)
If in doubt - model it backed up with professional experience and
test equipment.
Trust me - I do know ;-)
- Andy (I don't sell floor tiles) -
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