A Type of Planar Array-Antenna Feeding Network With Single/Multiband Filtering Capability

A dual-function circuit carrying out both the RF power-division and single/multiband filtering action is presented. It is used as building element to develop highly frequency-selective power-distribution networks for planar array-type antennas. The operating principle of this filtering/feeding circuit, exploiting transversal signal-interference techniques, is described. Also, formulas and guidelines helping in its theoretical design are given. As proof of concept, microstrip prototypes of four-way single- and triple-band filtering/feeding networks are built and tested.