A four‐pole single passband filter based on planar multilayered closed cavity with three magnetic side walls.

A double‐layered substrate three magnetic side wall cavity (TMSWC) and three‐layered configuration with stacked double TMSWCs are proposed. These structures can realize miniaturization by equivalent magnetic walls inside closed cavities and avoid radiation at the same time. Based on the above three‐layered form, a compact four‐pole single passband filter is designed and fabricated. The measured results agree well with the simulated ones. [ABSTRACT FROM AUTHOR]