Broadband Metamaterial-Based Dual-Polarized Patch Antenna With High Isolation and Low Cross Polarization

A broadband metamaterial-based dual-polarized (DP) patch antenna fed by a cross aperture coupling through striplines is investigated. A metamaterial-based radiating patch with <tex-math notation="LaTeX">4\,\,×4 </tex-math> cells is designed to achieve broadband radiation by generating two resonant modes with the help of a cross aperture antenna. The cross aperture antenna fed by two orthogonal feed networks is arranged right underneath the patch to obtain DP operation. Both the feed networks based on striplines are sandwiched by a pair of parallel metallic plates to reduce cross-polarization. Vias are used to enhance the isolation by suppressing the coupling among cross apertures and stripline-based feed networks caused by parallel-plate mode. Moreover, the working mechanism of coupling reduction is analyzed by characteristic mode analysis (CMA) and electric field analysis. A prototype of the antenna has been fabricated. The measured results indicate that the DP patch antenna exhibits impedance bandwidths (voltage standing wave ratio (VSWR) ≤2) of 46.9% for Port V and 45.8% for Port H. The cross-polarization levels above the ground plane are less than −28 dB, and the isolation better than 40 dB within the impedance bandwidth.