A design procedure of low dispersion beam forming networks

An array antenna with beam forming network (BFN) is used as a primary radiator of a reflector antenna in order to generate shaped beams. A BFN of tree configuration is composed of a number of unit circuits. A unit circuit in turn, is composed of a power divider and transmission lines. BFN is required not only to give the desired amplitude and phase distribution of the array antenna at the center frequency, but also non-dispersive characteristics, that is, to give a phase distribution independent of frequency. In this paper, a model of a power divider is proposed and a chart to select the type of power divider is shown. Based on the result, a design procedure of low dispersion BFNs is presented. In order to verify the procedure, a design example is presented