A High-gain Differential-fed Dual-polarized Filtering Patch Antenna with Wide Stopband Suppression

A high-gain differential-fed dual-polarized filtering antenna with broad out-of-band suppression is proposed. A ring resonator is attached to the antenna at the differential feed, along with the introduction of two low-frequency radiation nulls and one high-frequency radiation null. Furthermore, a novel high-frequency radiation null is formed by loading the SLR (stub-loaded resonator) structure, which improves the upper band’s edge selectivity and produces a broadband stopband suppression. The loading of U-shaped parasitic branches increases the current coupling path and broadens the working bandwidth. The proposed filtering patch antenna has a simple and compact structure and a low profile. It can reach a maximum gain of 8.72 dBi and an impedance bandwidth of roughly 10% (2.5-2.76 GHz). More than 30 dB separates the cross polarization from the main polarization, and the upper stopband can reach 1.5 f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> (f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> is the center frequency of the antenna), the lower stopband can reach 0.38 f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> , and the measured inhibition rate can reach 85%.