Design of Wideband Microstrip Patch Sub-Array

This article presents an aperture-coupled patch antenna working over X-band with wide frequency band and low cross-polarization. By adopting offset-aperture coupling feed, parasitic patch and parallel feeding network, a $2 \times 2$ broadband multi-layer microstrip array is designed. The array with 45° polarization is realized using a masterly parallel feeding network with power equally divided. Simulated results show, for the array, the impedance bandwidth with VSWR < 2 reaches 50% over X-band, cross-polarization levels are lower than −30dB.