A Low Cross-Polarization Multilayer Microstrip Linear-Array

In this letter, a 1x8 microstrip patch array based on multi-layer circuit board process is proposed. It eliminates the difficulty of conventional microstrip antenna that has decent high cross-polarization and narrow impendance bandwidth. To realize ultra-low cross-polarization the antenna element was fed by aperture-coupled technique, and the aperture is excited by symmetrical microstrip line; in order to suppress the backward radiation a ground plane is placed under the aperture. For the purpose of wide-band stacked patch and hollow substrate were adopted. To further reduce the cross-polarization at the array level we adopt the "mirroring" technique which enables the cancelation of the cross-polarized fields. The simulated results show that the array has a near 30% impendance bandwidth and scanning up to 50 degrees with VSWR < 2 (E-plane), the cross-polarization levels are below -60dB.