Miniaturized dual-band filters based on quarter-mode substrate integrated waveguide loaded with double-sided stepped-impedance complementary split-ring resonators

This paper presents two miniaturized dual-band filters based on quarter-mode substrate integrated waveguide (QMSIW) loaded with double-sided stepped-impedance complementary split-ring resonator (DS-SICSRR). The modified SICSRRs, realized by employing the stepped-impedance concept into the conventional CSRR, are with longer electrical lengths and thus exhibit more compact size as compared with its corresponding conventional CSRR counterpart. Subsequently, by loading the SICSRRs with different sizes into the two sides of the QmSIW cavity, two cavity resonators with dual-band response are realized. Since sizes of the SICSRRs on the two sides are tuned independently, the two passbands of the proposed resonator can be controlled flexibly. Based on the proposed QMSIW-DS-SICSRR cavity resonators, two dual-band bandpass filters are implemented, with their measured results in good agreement with the simulated ones. Compared with some related works, the two proposed dual-band filters exhibit size-reduction about 52% and 64%, as well as more controlling flexibility of the two passbands.