Novel Differential Dielectric Waveguide Filter Using Spatial Coupling Mechanism

This letter presents a novel differential dielectric waveguide (DW) filter using a spatial coupling mechanism. The DW resonator operating in TE
_20δ
-mode is reasonably cut and applied to the design of compact differential filter. Different from the traditional DW filter, the coupling between the DW resonators can be fulfilled by placing the cut planes of the DW resonators face-to-face in an open space. Meanwhile, the proposed differential filter can work well whether the employed DW resonators have the common ground plane or not, leading to a high flexibility. For demonstration, two kinds of differential DW filters with and without the common ground plane are designed and measured, and their simulation and measured results are presented. Both of them showcase high performance, such as low insertion loss of the differential-mode passband and good common-mode suppression.