Design of Dual-Band Filter Using Dielectric Resonator and Evanescent Mode Filters

In this paper, through the use of additional posts in irises of a dielectric resonator filter, a dual-band filter can be achieved. Metal posts, which can be realized using screws, are applied in the irises of dielectric resonator filters working as capacitive obstacles. These posts along with the irises and dielectric resonator enclosure, which work below cut-off, can form the resonators to function as an evanescent mode filter. With the existing dielectric resonator filter, a dual-band filter design can be achieved. Using a properly designed coaxial input/output structure, the two passbands can he tuned individually and then combined together. An example of the dual-band filter is designed and simulated to verify the design concept.