Ku-Band Groove-Gap-Waveguide Dual-Band Bandpass Filter With Multi-Transmission-Zero Sharp-Rejection Transfer Function

A high-selectivity dual-band bandpass filter (BPF) in groove-gap-waveguide (GGW) technology for Ku-band application is presented. It consists of a third-order GGW-cavity-resonator dual-band BPF block arranged in a split-type configuration with an additional oversized cavity inserted at its input access. The dual-band BPF block exhibits a third-order filtering response with three inter-band transmission zeros (TZs), while two more TZs between passbands and several TZs below/above the lower/upper passbands are produced by the input reactive load. In this manner, an overall sharp-rejection dual-band BPF response with multiple TZs being generated by two different mecha-nisms that avoid cross couplings is obtained. The RF operational principles and design foundations of the devised GGW dual-band BPF are detailed. Moreover, for practical-validation purposes, a proof-of-concept prototype corresponding to a 13.7/16-GHz dual-band BPF design example is manufactured and characterized.