Highly Configurable Cylindrical-Resonator-Based Bandpass Filter Built of Silica-Based Post-Wall Waveguide and Its Application to Compact E-Band Hybrid-Coupled Diplexer

This paper presents a compact and low-profile bandpass filter (BPF) built of silica-based post-wall waveguide. The BPF adopts direct-coupled resonator filters based on cylindrical resonators. The filter is highly configurable in shape and allows flexible and compact design. A compact E-band hybrid-coupled diplexer is presented as an application. The dimensions of the BPF and diplexer are 4.0×4.0 mm
²
and 9.4×9.9 mm
²
, respectively. The insertion loss of the lower passband of the diplexer is 1.52 dB at 72.9 GHz and that of the higher passband is 2.0 dB at 82.8 GHz.