Preliminary Studies of Beamwidth Controllable Circular Microstrip Patch Antennas

A beamwidth controllable circular microstrip patch antenna is proposed, with parasitic strips loaded on a flat, small ground plane. Two rectangular parasitic strips are symmetrically incorporated at the periphery of circular ground plane to yield an adjustable H-plane beamwidth. By changing the ratio of ground plane and patch size and the length of parasitic strips, the half-power beamwidth (HPBW) in H-plane can be controlled to vary from 63 ° to 149 °, with E-plane rarely changed. Experiments have shown that the HPBW ratio of the two principal-cut planes (i.e., H-plane and E-plane) can be adjusted from 1.82 to 2.