A single-layer dual-band shielded HMSIW bandpass filter using single SIW cavity

A single-layer dual-band shielded half mode substrate integrated waveguide (HMSIW) bandpass filter using single SIW cavity is proposed in this paper. A metallic wall is established along the longitudinal direction of the complete SIW cavity center and two gaps are etched near the metallic wall, two shielded HMSIW cavities are evolved from the single SIW cavity. These two shielded HMSIW cavities are coupled to each other by two interdigital structures. Moreover, TE101 and TE102 modes of both shielded cavities are utilized to form the lower and upper passband, respectively. Furthermore, complementary split-ring resonators (CSRRs) are used to easily adjust the frequency ratio of the two passbands, and a pair of open stubs are loaded on the feedlines to suppress the unwanted TE201 mode. The proposed filter is designed, analyzed, fabricated and measured. The tested results agree well with the simulated values. Two passbands with low insertion losses of 1.3 and 1.45 dB are centered at 3.03 and 3.92 GHz, respectively.