Dual-mode Folded Substrate Integrated Waveguide (FSIW) filters with LTCC technology

In this paper, a new kind of dual-mode Folded Substrate Integrated Waveguide (FSIW) filters in K-band with Low-Temperature Co-fired Ceramics (LTCC) technology is proposed. Dual-mode FSIW filter of single resonant cavity is designed to degenerate two modes: folded TE₂₀₁ and TE₁₀₂, which results in two transmission zeros on each side of the pass-band. To further validate its characteristics, a dual-mode working FSIW filter of two resonant cavities is proposed. In order to degenerate two modes, the I/O structures of these two filters are designed by an open microstrip line coupling through a rectangular slot on the ground plane.