Wideband U-slot patch antenna with reconfigurable radiation pattern

A wideband U-slot patch antenna with reconfigurable radiation pattern is investigated. The antenna composes three patches which are one coaxial-fed U-slot driven patch and two parasitic patches located near the two non-radiating edges of the middle driven patch. One varactor diode is installed in middle of each parasitic patch. Both beamwidth and main lobe direction can be tuned by controlling the direct current bias voltages of the two varactor diodes. The presented antenna has wide operating bandwidth of 6.4% at 1.4 GHz. Its beamwidth can be continuously changed from 60 degree to 130 degree and its main lobe direction can scan from -20 degree to +20 degree in the H-plane. Its peak antenna gain is 8.8 dBi with gain variation of 3.5 dB along the entire beamwidth tuning range and 8.5 dBi with gain variation of 2.5 dB along the entire beam scanning range. Simulation and measurement results agree well.