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Re: R: Quadrifilar home brew



>The main reason that i have experimented on 2400 MHz Quadrifilar Helix
>Antennas as per AMSAT Journal May/June 2004 was to find the way to
>produce a LHCP QFA to be used as a feed in a small dish having a low
>F/D ratio in the order of 0.3 to 0.35
>
>Pulling with you for P3E to verify the results !
>
>73" de
>
>i8CVS Domenico

Domenico,

I have just been studying the septum feed for eme use which is very simple to
build and provides both LHCP and RHCP.  I am giving some thought to building
one for my 85cm offset dish on 2.4 GHz.  Have you looked at this feed?  W1GHZ
did an exhaustive analysis of it in 2002 or 2003.  I will likey make a plain
one first, then add a sliding circular choke ring for comparison.  The basic
feed is good for f/d 0.35 dishes.  Either a flared horn or choke is needed for
f/d = 0.6 to 0.7.   At present I am using a 5-1/4 turn helix feed.

Here is a link to the septum design: http://www.ok1dfc.com/EME/emeweb.htm

73's Ed - AL7EB
http://www.qsl.net/al7eb
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