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Re: commutating antennas (was Re: Canted S-band antennason satellite)



On Fri, 3 May 2002, Franklin Antonio wrote:

> A different approach would be to put antennas on the sides, (perhaps 4 or 6
> sides), and let the satellite spin axis be roughly perpendicular to the
> orbit plane....
> For a satellite with a lot of different bands, like AO-40, this would be a
> big hassle, but for a satellite with lesser goals, with perhaps only one
> xmit band, this would not be difficult to do.

Neat idea!... but at near geo altitudes wouldnt it take about 24 sides
for maximum gain?  I think from that altitude, then the earth is less than
15 degrees across.  So for max gain, the antennas would need to have beam
widths of only about 15 degrees and so then you would need 24 of them to
cover one rotation of the bird.

BUT, I guess if you made them FAN beams that are wide in the plane of
rotation but only 15 degrees tall, then in fact, I guess you could do
that quite easily with a 6 sided satellite and only loose about 6 dB
from the maximum gain possible...

but for the simplicity, it could be well worth it..

Bob


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