Multi‐layered dual‐mode substrate integrated waveguide bandpass filter with input and output ports located on same substrate layer

Abstract

This study reports a multi-layered dual-mode substrate integrated waveguide (SIW) bandpass filter (BPF), in which the input and output ports are located on the same substrate layer (i.e. the upper one). The dual-mode SIW cavity in the lower substrate layer is coupled to the upper dual-mode SIW cavity by two crossed slots, which can independently control the inter-couplings. The proposed filter can be modelled by a dual-extended doublet coupling scheme with considering bypass couplings between source and load. Based on the proposed structure, single- and dual-band filtering responses with four controllable finite-transmission zeros (FTZs) are realised and analysed. For the demonstration, a single-band filter and a dual-band filter were fabricated and measured. The measured results agree well with simulated ones.