GBS/Milstar airborne RX and TX antenna

In 1999 an airborne Global Broadcast Service (GBS) and Milstar receive antenna was evaluated and successfully demonstrated in flight, atop an AFRL/IFG, C-135 SATCOM test aircraft. This Luneburg lens antenna received 20 GHz left hand circular polarization (LHCP) from a GBS terminal onboard the UFO-9 satellite and 20 GHz right hand circular polarization (RHCP) from a Milstar satellite. Phase II of this antenna adds a 44 GHz TX capability. This fully mechanically scanned antenna will still provide, ±80 degree coverage while rotating 360 degrees in azimuth. The hemispherical lens height was increased from 3 inches to 4 inches to increase gain and the lenses were redesigned with more shells to increase the efficiency for transmission at 44 GHz. A new feeder network was designed with 20 and 44 GHz horns to allow reception of 23.5 Mbps from the GBS terminal on the UFO satellites and to provide a medium data rate (MDR) transmit/receive (TX/RX) capability with the planned Milstar IV satellite. The 20/44 GHz antenna components, including Luneburg lens improvements and temperature test results are presented