Balanced Dual-band SIW Bandpass Filter With Enhanced Selectivity

Abstract

The contribution of this work is to propose a novel substrate integrated waveguide (SIW) dual-band balanced bandpass filter (BPF) with enhanced selectivity. In order to achieve this aim, both source-to-load and cross-couplings are employed by implementing four resonant nodes in two cavities, for the purpose of generating one pair of additional transmission zeros (TZs). Within this design, TE102 and TE201 are two dominant modes inside each cavity and each correlates with one passband responses. Due to their symmetric field distributions, balanced inputs/outputs can be assigned. The center frequencies of two passbands can be easily tuned by changing dimensions of cavities, while out-of-band skirt are tuned by changing dimensions of coupling slots. A second-order prototype is designed and fabricated for the demonstration. A good agreement is obtained between simulated and measured results.