Miniaturized Reconfigurable Dual-Band Bandstop Filter with Independent Stopband Control using Folded Ridged Quarter-Mode Substrate Integrated Waveguide

This paper presents a reconfigurable dual-band bandstop filter utilizing miniaturized folded ridged quarter-mode substrate integrated cavity. By loading a quarter-mode substrate integrated cavity with a capacitive ridge structure and folding the dominant field around said structure, significant miniaturization is achieved. Folded ridged quarter-mode substrate integrated cavity is shown to reduce the area of standard quarter-mode substrate integrated cavity by 92%, while also increasing the spurious-free region above the fundamental mode. A reconfigurable dual-band bandstop filter using miniaturized folded ridged quarter-mode technology is designed, fabricated, and measured. In order to generate independent tuning of each stopband, two resonators are each loaded with a tunable capacitance, and then individually coupled to the same nonresonating node, producing a frequency agile filtering section. Two filtering sections are then coupled together through an impedance inverter to produce a dual-band, two-pole bandstop filter. To the best of the authors' knowledge, this paper presents the first dual-band bandstop filter using quarter-mode substrate integrated cavity technology in the present literature.