High-gain low-RCS slot antenna array based on checkerboard surface

In-band and out-of-band radar cross-section reduction (RCSR) as well as gain enhancement for a slot antenna array is presented. The checkerboard surface (CS), combining an electromagnetic band gap structure and a metallic grounded slab, is adopted to realise a wideband RCSR. The analysis indicates a 10 dB RCSR of the CS compared with the perfect electric conductor surface can be achieved over 60% frequency bandwidth. Then, the designed CS is placed on the top surface of the 2 × 2 slot antenna array, and the measured results reveal that the proposed slot array possesses in-band and out-of-band RCSR from 5 to >12 GHz for both co- and cross-polarisations. Apart from the wideband RCSR, the gain enhancement is about 2.1 dB compared with the slot antenna array without the CS.