A dual-polarized antenna with pattern diversity

An antenna that is capable of exciting four different kinds of linearly polarized waves by four independent feeding ports across an overlapped frequency band is presented. The four polarizations embrace the x and y polarized waves, which have broadside patterns. And the 0 and o-polarized waves, which have conical patterns. The antenna can perform as a dual-polarized antenna for pattern diversity (broadside or conical) applications. The x and y polarizations ( TM/sub 11/ mode) and the 0 polarization (TM/sub 01/mode) are achieved by exciting a circular patch with four shorting posts and five L-shpaed probe fees. The o polarization is achieved by exciting four slots cut on the patch to produce radial magnetic currents. The performance of the antenna is studied numerically and experimentally. A prototype antenna was built, and the four polarizations overlapped at about 2.1 GHz. The antenna attained a gain of about 4 dBi for the two conical polarizations, and a gain of about 11 dBi for the two broadside polarizations.