Dual-Band 2×2 Cavity-Backed Antenna with Enhanced Out-of-Band Suppression for Tx/Rx Communication of UAVs at Ku-Band

This study introduces a dual-band linearly polarized 2×2 element cavity-backed antenna for unmanned aerial vehicles (UAVs). The proposed antenna can cover entire Rx (10.5‒12.5 GHz) and Tx (13.75‒14.5 GHz) bands of Satcom and datalink operations at Ku-band. The radiating part of the antenna contains four (2×2) radiating slots, which are excited by a coupling slot at the end of the feeding waveguide and a 2×2 cavity power divider. Additional baffles placed between radiating slots at the aperture are used to increase the bandwidth and gain values of in-band, and slightly improve out-of-band suppression. The antenna is fed by a rectangular waveguide, which includes two third-order E-plane band-stop filters being placed on the opposite sides of broad wall of the waveguide to significantly suppress out-of-band frequencies between Tx/Rx bands and below Rx band, which gives dual-band characteristics. The proposed full metal antenna has Rx and Tx bandwidths of 10.36‒12.54 GHz (|S
11
|< -10 dB; FBW = 16%) and 13.63‒14.7 GHz (|S
11
|< -10 dB; FBW = 7%), respectively. It has peak gain of 14.3 dBi with a stable in-band gain of 14.15 ± 0.15 dBi. Out-of-band rejection level of above 20 dB is obtained at the undesired bands of 9.8‒10 GHz and 12.8‒13.2 GHz.