L-band forward beam forming matrix

The INMARSAT-3 forward beam forming matrix interfaces between the forward IF processor and the L-band power amplifiers. Its purpose is to provide outputs to the antenna system, having pre-selected phase and amplitudes, in order to achieve a required antenna pattern. The unit is entirely passive and has 22 output paths, one for each antenna element. There are 8 divider panels, printed on microstrip circuit boards, and having novel components for achieving the required relative phase and amplitude for each of the 22 outputs from each panel. 22 combiner panels are mounted orthogonally to the dividers and connected via 50 ohm blind mate connectors, to provide the 22 output paths. The authors describe the electrical and mechanical design features and includes RF performance figures