A Low-Profile Dual-Polarized Patch Antenna With Stable Radiation Pattern Using Ground-Slot Groups and Metallic Ground Wall

A low-profile dual-polarized patch antenna with stable radiation pattern for use in base stations operating from 1.7 to 2.7 GHz is presented. The antenna consists of a square patch radiator placed at 20 mm (0.14λ0at the center frequency of 2.2 GHz) above a square ground plane. For bandwidth enhancement, the square patch radiator is dual fed using four probes, each having a U-shape. Two wideband 180° baluns are designed using composite right/left handed transmission lines to generate two signals with same amplitude, but phase shift of 180° for the probes. The radiation pattern is stabilized using four slot groups on the ground plane and a metallic ground wall around the radiating patch. The antenna is studied and designed using computer simulation. Results show that the simulated half-power beamwidths have variations of only 4° and 5° in the elevation (EL) and azimuth (AZ) planes, respectively, across the operating band. Measured results show that the antenna has the impedance bandwidths of 1.68-2.83 GHz and 1.7-2.85 GHz for the two input ports, isolation of more than 38 dB, and cross-polarization of less than -20 dB at the boresight in both the EL and AZ planes. The measured boresight gains are 7.8 ± 0.6 dBi for both two ports, and the radiation efficiencies are 74%-84% and 73%-82% for ports 1 and 2, respectively.