A novel compact dual-band half-mode substrate integrated waveguide bandpass filter

This paper presents a novel dual-band bandpass filter (BPF) using half-mode substrate integrated waveguide (HMSIW) technology for the first time. The proposed filter is at least six times smaller than its conventional substrate integrated waveguide (SIW) counterpart with similar filter specifications. A three-pole dual-band Chebyshev BPF with center frequencies of 1.05 GHz and 1.3 GHz is designed and implemented on RT/Duroid 6010LM substrate. The measured insertion losses are 1.7 and 1.8 dB and return loss is better than 12 dB for each passband. A notch at 1.14 GHz with rejection level of 50 dB provides excellent frequency separation between filter passbands. A transmission zero at 1.681 GHz provides a rejection level greater than 70 dB in close vicinity of the higher filter passband. Absence of even order resonances gives a rejection level greater than 40 dB from 1.45-2.71 GHz. To our knowledge, this filter is the state-of-the-art in dual-band BPFs using SIW technology.