Cross-Polarization Suppression of a Dual-Polarized Microstrip Antenna Using Enclosed Substrate-Integrated Cavities

An enclosed substrate-integrated cavities (ESICs) backed dual-polarized (DP) array with suppressed cross polarization for an X-band radar is investigated. Initially, stacked patches and cross aperture-coupled technique are utilized to achieve a wideband impedance matching and a DP operation. Additionally, a couple of multistage corporate feed networks based on the pairwise anti-phase feed technique are employed to suppress cross polarization over the operating band. Finally, five ESICs are inserted into the array to further suppress the cross polarization. A prototype of array is fabricated and measured. The measured results show that the DP array yields fractional bandwidths (VSWR ≤ 2) of 29.89% for Port H and 30.73% for Port V. The cross-polarization levels are better than –42 dB for V-pol and –44 dB for H-pol at 9.6 GHz, and the isolation between two ports remains above 39 dB over the whole operating bandwidth.