Dual-band full metal 2 × 2 cavity-backed filtering antenna with waveguide stubs on coupling slot

Abstract In this study, a dual-band full metal cavity-backed antenna, which has been modified from a wideband antenna, is presented for a Ku-band satellite communication systems (SatCom). The antenna consists of a feed waveguide, coupling slot, cavity-backed power division layer and radiating layer with slots and baffles. For filtering purposes, the stubs are inserted into the coupling slot which provides notches. They are intended to separate the Rx and Tx bands. This converts a wideband antenna into a dual-band antenna without changing the overall dimensions of the antenna. Moreover gain/radiation patterns in the Tx and Rx bands are not affected. The addition of stubs effectively rejects the out-of-band frequency region of 12.5–13.75 GHz between receive (Rx; 10.5–12.5 GHz) and transmit (Tx; 13.75–14.5 GHz) bands. Consequently, isolation and interference between the Rx and Tx bands is improved. The measured S-parameters for |S 11 | < −10 dB present the bandwidths of 2.18 GHz (10.42–12.6 GHz, FBW = 18.9%) and 0.87 GHz (13.83–14.7 GHz GHz, FBW = 6.1%) for Rx and Tx bands, respectively. Besides, the bandwidth of |S 11 | > −2 dB for the out-of-band region is 0.57 GHz (12.95–13.52 GHz), which gives dual-band characteristics. The measured peak gain of the antenna is about 14.9 dBi. The maximum out-of-band rejection between the Rx and Tx bands is about 19.2 dB at 13 GHz. The proposed antenna has compact dimensions of 1.7λ 0 × 1.5λ 0 × 1λ 0 at the lowest frequency of 10.4 GHz.