Scan Beam Antenna Intermodulation Improvement Due to Spatial Dispersion

In the recent development of scan beams for application tomobile satellite or thin route communication systems, theintermodulation (IM) generated by the element amplifiers isspatially dispersed, such that some of the IM radiated energy failsoutside the intended beam area. In addition, some of the IM fallinginside the beam area have frequencies different from the carriersintended for that area.It is shown that for systems with frequency reuse, an average IM noise reduction of several dB can he realized. The improvementin carrier-to-IM noise ratio can be used to increase system capacity,or for given capacity it can be used to reduce RF power amplifierbackoff, which can be translated into a reduction of spacecraftprime power requirement.