SIW-based enhanced gain self-diplexing antenna using higher order modes

Abstract

A self-diplexing antenna using slot-loaded cavity-backed Substrate Integrated Waveguide (CB-SIW) is presented with the enhanced gain. Higher-order modes (TE130 and TE310) in a square-shaped SIW cavity are utilized to emit linear and orthogonally polarized radiation with gain enhancement. Two concentric square ring slots are etched on the top conducting layer of the cavity to achieve broadside radiation. The asymmetric width of the outer square ring slot helps in achieving two different resonant frequencies at TE130 and TE310 modes. The proposed antenna is verified by observing a good match between the simulated and measured results. An excellent self-diplexing characteristic is achieved by getting isolation better than 28.0 dB between the two ports for a large tuning range. The proposed antenna radiates unidirectionally at two close frequencies 11.4 GHz and 12.2 GHz exhibiting gain of 9.8 dBi and 9.15dBi, respectively. In addition, the proposed design is single-layered, easy to fabricate as compared to traditional diplexing antennas.