Compact dual‐band filter using interleaved folded half‐mode substrate integrated waveguide resonator

Abstract

A multi‐layer interleaved folded half‐mode substrate integrated waveguide (HMSIW) dual‐band filter is proposed. The TE101 and TE102 mode of the HMSIW resonators form dual‐band response by vertical coupling, and the bandwidth of the two passbands can be independently designed by adjusting the coupling apertures. Moreover, three transmission zeros (TZs) are obtained to improve out‐of‐band rejection, and the TZs can be flexibly designed below or above the passband. By vertically superimposing the HMSIW cavity, the HMSIW filter can be extended to multi‐pole dual‐band filters. A dual‐band filter with centre frequency of 3.05 and 4.7 GHz was fabricated and measured to verify the proposed method. The simulated and measured results are in good agreement.