SIW Cavity-Backed Antenna-Triplexer for Radio Altimeter/Wi-Fi Applications

A new design of substrate integrated waveguide (SIW) cavity-backed antenna-triplexer is proposed for radio altimeter and Wi-Fi applications. The proposed design comprises two half-mode like SIW cavities and a rectangular patch. Both parts of the cavity and the patch are separated with the help of an annular slot on the top surface. The proposed design produces three distinct resonances around 4.2, 5.2, and 5.8 GHz, when the geometry is excited by two microstrip feedlines and coax-probe. To avoid mutual coupling among the ports, the patch is excited orthogonal to the cavity. The proposed design is fabricated and experimentally verified. The experimental results show good matching with simulations and an intrinsic isolation better than 23.5 dB is achieved between any two input ports which helps to realize a triplexing mechanism. Moreover, the proposed design has the advantages of low cross-polarization, higher gain with unidirectional radiation performance.