Design of a broadband cavity-backed multislot antenna

A novel cavity-backed microstrip-fed multislot antenna (CBMSA) for wideband application is proposed. The antenna is simply fed by a microstrip line terminated with a wide rectangular stub. By incorporating multi-slot configuration and backed cavity, unidirectional beam can be obtained within a broad bandwidth. The return loss, radiation pattern and gain over the antenna´s operational bandwidth have been numerically and experimentally studied. It is shown that the impedance bandwidth of the antenna is from 5 to 10.3 GHz, which is about 69% (for |S₁₁| lower than -10 dB). Good polarization purity with cross-polarization level lower than 18 dB and front-to-back ratio better than 12 dB are obtained. Hence, the antenna can be used in different broadband communication or identification systems.