Dual Band Cavity-Backed Filtering Antenna with Modified Coupling Slot Structure

In this study, the loading stub technique is proposed to convert a wideband 2 x 2 full metal cavity-backed antenna into a dual band antenna for satellite communication (SatCom) systems. A wideband 2 x 2 cavity-backed antenna is converted to a dual-band antenna by simply adding stubs to the conventional coupling slot structure, which act as a filter. The filtering antenna does not change the wideband antenna's lateral and longitudinal dimensions and does not distort gain and radiation characteristics within in-band frequency regions. By integrating these stubs, the undesired frequency band of 12.5 - 13.75 GHz between Rx (10.7 - 12.5 GHz) and Tx (13.75 - 14.5 GHz) in-bands at Ku-band is effectively suppressed, which improves isolation and lowers interference. The simulated fractional bandwidths (FBW) for vertical bar S-11 vertical bar <-10 dB are 15.78% (10.68 - 12.51 GHz) and 8.1% (13.74 - 14.9 GHz) at the Rx and Tx bands, respectively. The peak gain values range from 13.06 to 13.92 dBi at Rx and 13.57 to 14.24 dBi at Tx bands. Besides, the out-of-band rejection level reaches 20.7 dB at 13 GHz while covering the entire Rx and Tx bands of the Ku-band.