A Wideband and High Gain Dual-Polarized Filtering Antenna Based on Multiple Patches

This communication investigated a wideband filtering patch antenna with high gain and high selectivity. The antenna is mainly composed of an aperture-coupled driven patch, a stacked patch, and four center-shorted trapezoidal thin patches. The stacked patch can introduce a higher frequency resonant mode and a radiation null due to magnetic coupling. Four trapezoidal thin patches loaded with shorting vias are located around the driven patch, acting as a vertical split-ring resonator (SRR) and introducing a lower frequency resonant mode and a radiation null due to electric coupling. With two radiation nulls at the edges of the passband, the filtering gain response with high selectivity is achieved. As no filtering circuits are used, the antenna can obtain high gain and high efficiency. Due to the symmetrical structure, a dual-polarized filtering antenna is also presented for base-station application, demonstrating good radiation performances and an isolation of 20 dB. A fabricated dual-polarized antenna is measured, showing a wide bandwidth up to 18.8% (from 3.19 to 3.85 GHz), a peak gain of 9.5 dBi, and two near-band radiation nulls located at 3.13 and 4 GHz.