Enhanced Cross-Polarization Discrimination of Wideband Differentially Fed Dual-Polarized Antenna via a Shorting Loop

In this letter, a wideband differentially fed ±45° dual-polarized antenna with high cross-polarization discrimination (XPD) is proposed for base station applications. The antenna is composed of a pair of orthogonal bowtie-shaped dipoles backed by a ground plane, which are differentially fed by four coaxial cables through a cross-shaped feeding line. Four fan-shaped parasitic patches are employed to enhance the impedance bandwidth. A shorting loop that is connected to the ground plane via pins is utilized to improve XPD across the desired band. A prototype of the antenna is fabricated. Measured results show that the antenna has a wide overlapped impedance bandwidth of 48% (1.68-2.74 GHz) at two ports for differential VSWR <; 1.5 and a high differential port isolation of 35 dB. Also, a stable gain of about 7.9 dBi and a stable radiation pattern with 3 dB beamwidths of 70° ± 4° are obtained. Besides, the measured XPDs are better than 20 dB at the boresight and better than 10 dB at elevation angles of ±60° of the main lobe in the horizontal plane over the band of operation.