24 GHz Amateur Radio Band

for the first server sky experiments

The first server sky experiments may use the 1.2 centimeter ham band, 24.00 to 25.05 GHz, transmitting to a global network of amateur radio operators for the ground stations.

Assume a test array of 50 12x12 centimeter 2 watt 5 gram thinsats (100 watts total power), deployed from a 2U cubesat. Effective transmit power, perhaps 2 watts, effective transmit antenna area, 12 x 600 centimeters, making a steerable asymmetric beam 0.1 by 0.002 radians, EIRP 125 kW. From GEO (40,000 km path length), with a 2 meter tracking receive dish, that would deliver 20 picowatts to the receiver. Assuming kT = 0.05 eV = 8e-21 J at 600 K effective noise temperature, and 5 kT per bit, that is 4e-20 W/bps, or 500 Mbps - more than a 50 MHz channel can support. Assume 100 Mbps downlink, 50% duty cycle; plenty of bandwidth to return a lot of scientific information from the test array.