Compact diplexer with high isolation based on mixed‐mode triangular substrate integrated waveguide cavities

A novel compact diplexer based on mixed-mode isosceles right triangular (IRT) substrate integrated waveguide (SIW) cavities is presented. dual-mode IRT SIW junction cavity direct-coupled with two single-mode for lower and upper channels, respectively. The has third-order filtering centred at 16 18.3 GHz 400 422 MHz bandwidths. in-band measured return insertion losses are 19 dB/1.3 dB in the band 17 dB/1.36 band. Due to orthogonality of TE102 TE201 modes cavity, high isolation (>45 dB) between channels obtained. Besides, proposed also advantages low cost easy integration other planar circuits.