Triple mode conductor loaded cavity filter

In this paper, a new triple mode conductor loaded cavity resonator is presented. The resonator consists of a cubic shape metallic structure mounted in a metallic enclosure. A low loss, low dielectric constant support structure is used to hold the metallic resonator inside the cavity. The proposed resonator, operating at the TM
_01delta
mode, is similar to the triple mode dielectric resonator, where the dielectric constant of the resonator approaches infinity. The triple mode conductor loaded cavity resonator is considerably cheaper, easier to design and manufacture, and offers a significantly wider spurious free response in comparison to the triple mode dielectric resonator. A six-pole filter employing the proposed resonator is design using full wave EM simulator. Introducing asymmetry in the structure of the metallic resonator in the form of chamfers provides the required coupling between the degenerate modes inside each block to realize the desired filter response. The six-pole triple mode conductor loaded cavity filter is fabricated and tested. The measurement results verify the validity of the proposed concept. The triple mode conductor loaded cavity resonator can be combined with higher Q-factor triple mode ceramic resonators to realize a small size, high Q-factor filter with wide spurious free response.