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Re: 2,4Ghz/LHCP-RHCP...???



All AO-40 antennas are RHCP. Since the polarization is reversed by
reflection, a helix used to feed a dish should be LHCP. The number of turns
depends on the focal length to diameter ratio of the dish, but will be in
the range of 3-5 turns. AMSAT has published detailed information in the
past -- get a copy of the Satellite Anthology or the more recent publication
on P3D.

A long (appx. 20 turn) helix should also work and has less windload. The
ARRL Antenna Book has information on this type of antenna. Put a
counterwieght behind either type of antenna to balance the load on the
elevation rotator.

73,

John
KD6OZH

----- Original Message -----
From: "Jens Spiess" <jspiess@dplanet.ch>
To: "AMSAT" <amsat-bb@AMSAT.Org>
Sent: Saturday, 02 December 2000 00:30 UTC
Subject: [amsat-bb] 2,4Ghz/LHCP-RHCP...???


> Hello...
> what polarization should be used for receiving the
> 2,4 GHz downlink of Ao40....LHCP or RHCP ?
> Or it`s better to have both available..?
> How many helix-turns are recommended into a
> 60 cm parabolic dish..?
> And for 1,2 GHz UPLINK...LHCP or RHCP or both,
> to change for the best S/N...?
> (Note: I had never worked before mode =S=...)
>
> 73,Jens / HB9JOI (DL9FAA)
> AMSAT-DL.#9802268
> e-mail: jspiess@dplanet.ch
>
>
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>

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