Low-Cost Dielectric-Resonator Filters With Improved Spurious Performance

A dielectric-resonator filter configuration implemented as a single piece of a high-K ceramic substrate is presented in this paper. The proposed filter configuration considerably reduces the cost of the assembly and the integration associated with conventional dielectric-resonator filters. A two- and four-pole filter of this type operating in the TEH₀₁ fundamental mode have been developed, manufactured, and tested. Theoretical designs of the filters are confirmed and supported by measurement results. The wideband spurious performances of the filters are investigated and the improvement of the spurious response is demonstrated theoretically and experimentally for both two- and four-pole filters. Furthermore, a novel triplet structure based on the proposed concept is presented, which provides a new approach to implement nonadjacent couplings for the realizations of asymmetric filtering characteristics. The proposed dielectric-resonator filter configurations can be potentially used to implement dual-mode dielectric-resonator filters. The concept is very attractive for use in low-cost high-Q mass production of wireless filter applications.