[amsat-bb] HF Satellite Relay

Robert Bruninga bruninga at usna.edu
Mon Jun 28 10:44:45 PDT 2010

Heard today of a Passive HF relay satellite being proposed.
Wondered if Hams could relay off of it.

It's a 10m diameter sphere.
I assumed a 10m signal and 1000 Watts
And antenna gains at both ends of 10 dB.
Unless I made a dumb error, it looks impossible?
I get a received signal of -170 dBm
Compared to a good HF receiver of -122 dBm
So its 48 dB down in the noise.
Going to narrow band, could improve things, but the Doppler of
+/- 600 Hz would make that difficult.

Anyway, if someone else wants to double check the link budget
using the radar range equation, go for it. 

The beauty of this system is that it is perfectly spherical, so
the reflection coefficient would be constant within 1 dB.  That
is the advantage over trying to use the ISS or other large
rocket body... They vary by 20 dB making communication by
reflection impossible.

Oh, and it would be in space for 30 years or more.  So with
something that reliable, it would be worth developing an amateur
capability to use it.
It is not designed for comms, but as a calibration sphere for
over the horizon radars that have LOTS more power and LOTS more
gain than we do.

Bob, Wb4APR

More information about the AMSAT-BB mailing list