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RE: Ao-40 site question



Hello David

> I'm in Houston, TX---it appears
> that AO-40 will always be south of me (judging by a predicting a few
> passes).  Will this trend hold long term?  Ie: can I get away with a
> site that can only see ~90-270 degrees azimuth?

Yes. For your location, AO-40 will always be south of you. Its maximum
aberration from the equatorial plane is about 10 degrees.

> Just
> curious, will a 0db discone without a preamp be able to hear any of the
> LEOs?  That would be cool.

Depends to a large extent on the coax losses from the antenna to the
receiver and to some extent the receiver sensitivity. In general you will be
able to hear LEOs with this, but it will be intermittent throughout the pass
due to polarisation mismatches, lobe nulls and ground reflection nulls. The
huge benefit gained from using an HT with an end fed dipole whip on the 70cm
downlinks is that you can move the radio manually to attain the best signal
and maintain almost continuous coverage.

I discone also has its main lobes concentrated at the horizon, which is
great for terrestrial use but hampers space communications because of all
that ground noise being picked up as well as a big hole in the radiation
pattern when the birds make some of the higher passes.

The VE3VRW satellite gateway in Toronto
http://members.rogers.com/va3sf/gateway.htm uses small (4' or 5' boom)
directional antennas to maintain horizon to horizon unattended coverage.

73 Howard G6LVB


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