Compact dual‐band inverted‐microstrip ridge gap waveguide diplexer

Abstract

A compact dual-band inverted microstrip ridge gap waveguide (IMRGW) diplexer composed of four dual-mode IMRGW resonators and an IMRGW T-junction matching network is proposed in this letter. The dual-band diplexer is based on a dual-mode IMRGW resonator which can produce both the inverted microstrip resonant mode and the cavity resonant mode. Two resonant modes of the IMRGW resonator are highly independent, so the passbands of dual-band IMRGW diplexer can be easily tuned to the desired frequencies. A second-order dual-band IMRGW diplexer is designed and simulated. The simulated passbands of the second-order dual-band IMRGW diplexer are 13.13-13.38, 14.85-15.26, 18.57-19.42, and 20.85-21.35 GHz with fractional bandwidth of 2%, 2.7%, 4.8%, and 2.4%. A prototype is fabricated and measured to verify the feasibility of the proposed IMRGW diplexer. The measured passbands of the second-order dual-band IMRGW diplexer are 13.07-13.35, 14.88-15.35, 18.45-19.37, and 20.82-21.28 GHz with fractional bandwidth of 2.1%, 3.1%, 4.9%, and 2.2%. The measured isolation is better than 23 dB over 12-22 GHz. The measured results agree well with the simulations.