Dielectric Resonator Elliptic-Function Band Rejection Filter with External Coupling Waveguide

A Ku-band elliptic-function band rejection filter (BRF) has been developed which employs a rectangular waveguide, dielectric resonators (DRs), and an external coupling waveguide to obtain attenuation poles. The high-Q DRs and the coupling waveguide realize larger attenuation with smaller number of stages than that of conventional all-pole BRFs like Chebyshev or maximally-flat response. The BRF is designed on an equivalent circuit, which has symmetry and thus enables simple even- and odd-mode analyses. The external waveguide is connected to the BRF through coupling slots in E-plane of main waveguide to obtain negative coupling between the DRs.