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Re: QUAGI vs HELIX vs QUAD



Andrew,
Helix antennas being circulary polorized have rejection to the opposite 
rotation generaly caused by reflections provided that both sides are of the 
same circular polorization. Reflections from buildings etc can cause signal 
cancelation as well as combining reflections as the satillite moves 
overhead.
In addition the satellite spin does not effect the signal strength on a 
circularized antenna even if the satellite uses a linear antenna.

When the satellite is at low elevation the linear antenna may work quite 
well as there ae few strong reflections. This assumes the you are tracking 
the satellite with both antennas during the pass. If the satellite is 
antenna is pointing away from you the rotation polarity is reversed causing 
you not to receive the satellite or hear it very weakly. Then the Vertical 
antenna will work better than the Helix.
Art,
KC6UQH

----- Original Message ----- 
From: "Andrew Rich" <vk4tec@people.net.au>
To: "Amsat-Bb@Amsat. Org" <amsat-bb@amsat.org>
Cc: "Aprssig" <aprssig@lists.tapr.org>; "ozaprs" <ozaprs@aprs.net.au>
Sent: Friday, December 07, 2007 1:51 AM
Subject: [amsat-bb] QUAGI vs HELIX vs QUAD


> Today I built and compared two 70 cm antennae against various satellites.
>
> The first antenna was a RHCP helix with 9 turns
>
> The second antenna, a 8 element quagi. (vertically)
>
> The clear winner was the helix.
>
> Anyone had similar experiences ?
>
> I remember way back about 10 years ago, i built a quad with a metal boom,
> and it picked up better side on. (not good)
>
> I have kept to an 8 element quad on 2meters, it is really good.
>
> I can key up a repeater some 150 km's away and i am in a ditch.
>
>
>
> ----------------------------------------------------------------------------
> Andrew Rich VK4TEC
> vk4tec@people.net.au
> http://www.tech-software.net
>
>
> _______________________________________________
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