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Re: Re: S Band Helix



The one effect is the PVC inside will cause some refraction of the wave
front the amount depending on thickness of the PVC. this effect will limit
the gain on helix over two wavelengths long.

Art, KC6UQH
----- Original Message -----
From: "John M. Belstner" <jbelstner@yahoo.com>
To: <amsat-bb@amsat.org>
Sent: Thursday, June 16, 2005 12:08 PM
Subject: [amsat-bb] Re: S Band Helix


> The inherent broadbandedness of the Helix design greatly mitigates this
effect.
>
> John W9EN
>
> ------------------------------
>
> Message: 6
> Date: Wed, 15 Jun 2005 23:40:15 -0400
> From: "Woody" <kj4so@nc.rr.com>
> Subject: Re: [amsat-bb] S Band Helix
>
> Hi Robert:
>
> PVC is a dielectric and when placed in close proximity to an antenna,
> will lower the resonant frequency of the antenna, compared to the same
> antenna without any type of raydome or enclosure.  This effect is due to
> the lowered VOP (velocity of propagation) of the PVC.
>
> PVC makes a good Raydome for a 2.4 GHz. antenna, you just need to
> compensate for the lowered resonant frequency of the antenna.
>
> 73,
>
> Woody
> KJ4SO
> AMSAT # 5562
> ----
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