An annular-slot coupling feeding technique for dual-feed circularly polarized patch arrays

A dual-feed circular patch coupled to the microstrip feeding line through an annular slot has been used to realize a circularly polarized 2x2 array. Simulation results are compared with those for a 2x2 array composed of 4 dual-feed square patches coupled to the microstrip feeding line through a square ring slot. Simulations results for the two arrays both designed to operate in the WiMAX™ frequency band have shown. AR<;0.6dB and a Return Loss greater than lOdB can be obtained in the 3.3-3.8 GHz frequency band, with a stable array gain of about 12.8dB. The circular configuration exhibits better results in terms of impedance matching bandwidth and axial ratio performance, with respect to the square patch array. Measurements on array prototypes will be shown at the conference.