Re: [amsat-bb] Helix Feed for a Dish

["John Stephensen, KD6OZH" <kd6ozh@xxxxxxx>]

The dimesions suggested by Kraus in "Antennas" for a cylindrical cup are
3/4-1 wavelength in diameter and the same length as the helix. Mine is 4"
square by 2-1/4" long.

73,

John
KD6OZH

----- Original Message -----
From: "Woody" <kj4so@bellsouth.net>
To: <amsat-bb@AMSAT.Org>
Sent: Wednesday, 06 June 2001 02:36 UTC
Subject: Re: [amsat-bb] Helix Feed for a Dish


> Hi All:
>
> There have been many very interesting messages on the BBS lately on the
use
> of a "cup" style reflector on a helix dish feed antenna to reduce the
> sidelobes and thereby reduce noise pickup on S-band dishes.
>
> However, I have not seen any discussion on the size and depth of the cup
> reflector.  Has anyone experimented with various diameter cups as well as
> the depth of the cup?  The diameter and depth of the cups would be very
> helpful to many people, myself included.
>
> Does the diameter and depth of the cup change between feeds used for an
> off-set feed dishe, versus a center-focus parabolic dishe?
>
> Is a 2 1/4 turn helix sufficient for use with a .9 meter, center-focuse
dish
> with a focal length of .45?
>
> Thanks & 73,
>
> Woody
> KJ4SO
>
>
>
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