Compact, Vertically Integrated Duplex Filtenna With Common Feeding and Radiating SIW Cavities

Abstract

In this communication, a compact vertically integrated full-duplex filtenna is developed by using common feeding and radiating substrate integrated waveguide (SIW) cavities. A rectangular dual-mode SIW cavity, operating at its two orthogonal TE120 and TE210 modes, is first employed as the common feeding cavity to realize two passbands. And then, a common radiating square slot-loaded SIW cavity is vertically integrated with the common feeding cavity so as to enhance the operational bandwidth and improve the frequency selectivity for both two passbands. Two metallic posts are utilized to achieve the desired coupling strength between the feeding and radiating cavities for the two passbands, respectively. By properly arranging the locations of two input ports and coupling regions, high isolation between the two input ports is realized. The detailed design process based on the coupling matrix is presented. To verify the proposed concept, a prototype is fabricated and measured. The measurement results agree well with the simulated values, showing the maximum broadside realized gains of 4.36 and 4.83 dBi, and the impedance bandwidths of 3.2% (4.03–4.16 GHz) and 3.9% (4.81–5 GHz) for the lower and upper passbands, respectively. The proposed antenna also exhibits good performance in terms of port isolation, flat in-band gain response, and out-of-band frequency selectivity.