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Re: AMSAT-BB-digest V2001 #103



In a message dated 2/11/01 1:06:59 AM GMT Standard Time, 
owner-AMSAT-BB-digest@AMSAT.Org writes:

<< Date: Sat, 10 Feb 2001 18:42:30 -0000
 From: "Howard Long" <howard@howardlong.com>
 Subject: RE: [amsat-bb] Mode-S Antennas
 
 Hello Mark
 
 I re-ran my ever so scientific tests on the following 5 S-band antennas:
 
 15 element yagi Maplin Electronics (UK) www.maplin.co.uk Yagi 2.4GHz antenna
 cat # DS30H
 20 turn LHCP Helix homebrew based on K5OE, G6LVB mods
 20 turn RHCP Helix homebrew based on K5OE, G6LVB mods
 20 turn RHCP Helix Sandpiper Communications (UK) no web presence
 30 turn RHCP Helix Wimo www.wimo.com Helix 13-2 cat # 18029
  >>

Hi.

Forget the Sandpiper helix antennas. They don't have any matching section.

We tested the 23 and 13cms versions at the Amsat UK colloquium last year and 
found the impedance way off 50 Ohms. Return loss was between 6 and 10dB.

Both were significantly outperformed by a couple of home brew antennas from 
Ed's Mode S handbook.

73

David  G0MRF
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