In response to Joe, W9SBD, at 24 Ghz:

6' antenna = 51 dB gain, 3dB BW = .4 deg, EIRP @1W = 126 KW 4' antenna = 48 dB gain, 3dB BW = .6 deg, EIRP @1W = 63 KW 18" antenna = 39 dB gain, 3dB BW = 1.6 deg, EIRP @1W = 8 KW

All figures rounded to next whole number, gains assume 65% efficiency.

We have excellent space allocations at 3.4 GHz for downlink that would be very inexpensive to build. Even a high end 30 deg./K LNB with external 10 MHz. reference is less than $500 new and will convert 3.4 Ghz to 950 Mhz. The used price is much lower. I have sketched out some ideas to compensate and downconvert a really cheap ($50) DRO LNB to a 432 MHz. IF using mostly off the shelf parts. This band is great for space comms and can use very inexpensive commercial parts. There is very little terrestrial activity to worry about and this band is not allocated for commercial downlinks in this region. In areas where it is allocated, the frequencies below 3.410 don't seem to be popular commercially.

Howie AB2S