A Dual-Band Electrically Tunable QMSIW Filter

A tunable center frequency dual passband filter based on quarter-mode substrate integrated waveguide(QMSIW) resonator is presented. Second order complementary spiral resonator (CSR2), spurs line and defected microstrip structure (DMS) are added to the quarter-mode substrate integrated waveguide(QMSIW) structure to realize the miniaturization of the filter. At the same time, the introduction of spur line and DMS can suppress the generation of harmonics and improve the performance of the filter. The filter is connected with the bias circuit, and the first center frequency of the filter is continuously adjusted by continuously adjusting the voltage of the bias circuit. The designed filters are fabricated and measured to validate the present approach.