An E-band hybrid-coupled diplexer built of silica-based post-wall waveguide

This paper presents a low-profile and low-loss diplexer for E-band applications. The diplexer is realized by using a post-wall waveguide fabricated into a 0.52-mm-thick silica-substrate and consists of two five-pole Chebyshev bandpass filters and 90deg hybrids. The size of the diplexer is 29.7×5.7 mm
²
. The insertion-loss of the lower pass-band is 1.41 dB at 73.3 GHz and that of the higher pass-band is 1.65 dB at 83.5 GHz.