[amsat-bb] Re: Polarity questions
ve9qrp at gmail.com
Fri Sep 19 13:02:03 PDT 2008
A follow-up question --
I'd like to homebrew a circularly polarized antenna. Does anyone have
a favorite relay switch to use for this application? A lot of them
seem not to be weather-proof. It seems BNCs would make good
connectors, but I'd be interested in opinions on this, too.
On Fri, Sep 19, 2008 at 1:34 PM, Jim Jerzycke <kq6ea at pacbell.net> wrote:
> Theoretically, it's 'infinite', but out in the real world, expect around 20~25dB loss from being completely cross-polarized. When I was doing commercial satellite work, if we could get 26~27dB we were happy, but this was with rigidly controlled satellites and commercial ground stations.
> Between linear and circular, expect about 3dB loss.
> Jim KQ6EA
> --- On Fri, 9/19/08, Tim Tapio <tim at timtapio.com> wrote:
>> From: Tim Tapio <tim at timtapio.com>
>> Subject: [amsat-bb] Polarity questions
>> To: amsat-bb at amsat.org
>> Date: Friday, September 19, 2008, 5:58 AM
>> How much signal reduction is there as the result of having
>> the wrong
>> circular polarization?
>> I'm looking at M2 circular antennas for the 70cm
>> downlink, it's another $200
>> for the switching to change polarity (woo hoo).
>> 73 de Tim, K4SHF
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