A Broadband Dual-Polarized Antenna With Front-to-Back Ratio Enhancement Using Semicylindrical Sidewalls

A novel dual-polarized antenna, with a large bandwidth and a high front-to-back ratio, is proposed in this communication. The antenna is composed of printed dipoles and tapered baluns above a square ground plane to yield a wide bandwidth. Semicylindrical walls are loaded on the edge of the ground plane to suppress the back lobe and produce a stable gain. Backward radiation is suppressed by the diffraction effect of the semicylindrical sidewalls. Simulation shows that the back-lobe level can be reduced below -13 dB in a large frequency range without degrading the antenna bandwidth. The proposed antenna is fabricated and the measured results show that it has an impedance bandwidth of 69.6% (1.46-3.02 GHz) for voltage standing wave ratio <;1.5. Within the bandwidth, the gain varies between 7.1 and 8.4 dBi, and the front-to-back ratio is above 20 dB. The proposed antenna is suitable for outdoor base station applications, and the back-lobe suppression technique can be applied easily to base station antennas.