Compact QMSIW quasi-elliptic filter based on a novel electric coupling structure
A compact quarter-mode substrate integrated waveguide (QMSIW) quasi-elliptical bandpass filter is presented based on a novel interdigital-like capacitive coupling structure. This type of electric coupling structure is very suitable for the open boundary to implement the cross-coupling in classical quadruple topology. By this characteristic, a QMSIW quasi-elliptical filter working at 5 GHz is designed to demonstrate the superiority of this structure to the electric walls. Benefitting from the QMSIW technology, the wide-stopband feature is intrinsically achieved for the filter and the first spurious resonance is occurred at around two times the centre frequency.
