High Performance Beam Forming Network for Multi Contoured Beam Antennas

A compact Beam Forming Network (BFN) for contoured beam antennas has been developed and tested in the 10.9 to 12.8 GHz band (16%). The BFN components are designed with efficient electromagnetic tools to reduce the insertion loss and the amplitude and phase spreadings at the output ports. Particular care has been dedicated to the mechanical design in order to minimize the mass, to avoid critical resonances and thermal gradients. The BFN is composed of two independent sections connected together. These are the power divider section with sixteen output signals and the phase shifter section which establishes the correct phase distribution. The BFN utilizes as key components branch guide couplers and ireses phase shifters whose the predicted electrical characteristics are in excellent agreement with the experiments. Moreover an innovative technique is adopted to compensate the phase errors of the network in the relative wide band without additional tuning elements.