A Dual-Polarized Filtering Antenna Based on Crossed-Dipole

A dual-polarized filtering antenna with radiation nulls based on crossed-dipole is proposed in this letter. The antenna consists of three parts, including two baluns, a ground plane, and a metal wall. Two dipole arms are directly integrated into the balun structure to ensure balanced current distribution. By loading two bent λ/4 open-circuited stubs along the microstrip feedline of the balun, filtering performance is obtained as two radiation nulls are generated at the lower/upper edges of the operating band. Additionally, with the introduction of metallic wall, the in-band gain stability is enhanced while the front-to-back ratio (FBR) is improved. For demonstration, the proposed antenna is fabricated and measured. The simulated and measured results demonstrate that better than 15 dB out-of-band suppression levels are realized. Moreover, the proposed antenna achieves −10 dB fractional impedance bandwidths of 27.8% and an average in-band realized gain of 7.5 dB, making the proposed antenna a promising solution for dual-polarized filtering antenna.