Design of High-Selective Printed-Ridge Gap Waveguide Filter Using Source–Load and Cross Couplings

In this letter, high-selective bandpass filters, in the printed ridge gap waveguide technology, are presented. The filters are designed to perform 4.68% fractional bandwidth at center frequency f
₀
= 24.78 GHz. In the proposed filters, to obtain high selectivity, a cross-coupling between the nonadjacent resonators and also a coupling between the input and output ports to create an extra pair of transmission zeros in the transfer function of the filters are used. Finally, the filters are fabricated, and their scattering parameters are measured to verify the simulation results.