Beam Width Controlling Technique of Microstrip Patch Antennas Using Small, Flat and Stub-Loaded Ground Plane

Abstract

A square microstrip patch antenna with small, flat, stub-loaded ground plane is presented. In this manner, the currents on the ground plane can be utilized and manipulated to contribute an adjustable broad beam width characteristic. On the one hand, two parasitic rectangular strips are symmetrically incorporated on the small ground plane of a square microstrip patch antenna to reduce the back-lobe radiation and expand the beamwidth. On the other hand, with the change of ground plane size and stub length, H-plane half-power beamwidth (HPBW) can be remarkably adjusted to vary from 99° to 217°, with the E-plane one less changed. Experimental studies have been performed to verify the design technique. As can be seen, ratio of H-plane and E-plane HPBW can be tuned from 1.45-2.45.