Substrate Integrated Waveguide Multiband Bandpass Filters and Multiplexers: Current Status and Future Outlook

Multiband bandpass filters (BPFs) and multiplexers are essential front-end modules in the development of multifunction, multistandard, and multiband wireless communication, sensing, and positioning systems that are required in current and future intelligent electronics applications. In this paper, numerous implementation schemes and topologies of multiband BPFs and multiplexers, which have been proposed, studied, and developed so far, are holistically summarized and elaborated in terms of their merits and drawbacks. Subsequently, various technical approaches and diverse design methodologies based on substrate integrated waveguide (SIW) technology are thoroughly examined and reviewed with respect to technical features, electrical performances, and practical applications. Finally, future research and development directions and prospects of SIW multiband BPFs and multiplexers are briefly unraveled.