I agree with your observation that terrestrial microwave transmissions
towards stationary satellites would be difficult to detect from great
Many years ago, I was associated with a company that supplied television
programming to a domestic satellite (USA). We used a ten-meter dish at
uplink site. Effeciency was about 50% at 6.0 GHz, gain was around 53dB.
Beamwidth was about 0.35 degrees at the 3 dB down points (quite narrow).
Although the transmitter was capable of putting 3 KW into the feed, the
satellite operators in Vernon Valley, NJ would direct us to run with
less than 0.5 KW, to avoid saturating the transponder. On top of that,
36 MHz wide analog FM video was dithered at the field rate, to avoid
interference with terrestrial users in the same band. If video were
the dithering signal would insure that there were no "pure" carriers
This is all old technology. Many users (both C band and Ku band) are
to digital modulation schemes. From what I hear, these schemes leave
less of a "steady carrier" on which to integrate at the receiver.