Half mode substrate integrated folded waveguide (HMSIFW) and partial H-plane bandpass filter

Abstract

In this paper, a half mode substrate integrated with folded waveguide (HMSIFW) and a HMSIFW partial H-plane bandpass filter are proposed. The proposed filter employs H-plane slot of open-ended evanescent waveguide and H-plane septa of short-ended evanescent waveguide as admittance inverter and impedance inverter, respectively. The filter has advantages of convenient integration, compact size, low cost, mass-producibility and ease in fabrication. In order to validate the new proposed topology, a four-pole ultra-narrowband bandpass filter, with quarter wavelength resonators, is designed and fabricated using standard printed circuit board process. The tapered line is used as transition between HMSIFW and microstrip-line for easy integration and measurement. The measured results are in good agreement with simulated ones, and good selectivity is achieved.