SINGLE-FEED DUAL BEAM SWITCHABLE ARRAY ANTENNA FOR ISM BAND APPLICATION

Abstract

This manuscript proposes one single-feed dual-beam switchable array antenna and one single-feed multi-beam switchable array antenna. The proposed antenna contains three and four microstrip square patch antenna elements and a switchable feed network respectively. In dual-beam design, the feed network creates a 900 phase difference between the center element and the right or left antenna elements. This antenna can tilt its main beam direction to θ = by exciting either right or left antenna elements along with the center patch through two PIN diodes, respectively. The dual-beam switching concept is experimentally verified with better than 8 dBi gain for every condition at ɸ = 00-plane. The proposed multi-beam array antenna has two 900 switchable phase shifters. The 900 switchable phase shifter consists of a single-pole double-throw (SPDT) switch and a hybrid coupler. The hybrid coupler generates a 900 phase difference between the antenna elements to tilt its radiation pattern. The two SPDT switches can generate three modes to control the input ports of the hybrid coupler. As a result, two tilted beams and one difference pattern are generated from the same structure. A prototype multi-beam antenna is fabricated to demonstrate the concept experimentally. The measured results confirm the concept with a good agreement between the simulation and measurement. Better than 20dB cross-polarization suppression is achieved in the measurement.