A multi-layer X-Band microstrip array with beam tilt for FMCW-SAR application

A multi-layer tilted beam planar microstrip array for FMCW-SAR application is presented. The proposed 8×4 array antenna exhibits a beam tilt of 30 degrees in E-plane with a sidelobe level of 18dB and 20dB in H-plane without tilt. The inherent radiation pattern degradation of the array due to feed radiation is minimized with the proposed multilayered concept. The proposed design exhibits an improvement in sidelobe level of the order of 6dB in both E-and H-planes with better cross-polarization level. In the multi-layered design, the common ground plane separating the two stacked substrate layers, shields the antenna half-space from spurious radiation emitted from the feed network. The simulation results show that the radiation pattern in the operating frequency provides a 3dB beamwidths of 25° and 9° in E-plane and H-plane respectively. Array exhibits a gain of 20dBi at the centre frequency and cross polarization level of better than 15dB.