Design of dual- and triple-passband bandpass filters with interdigital resonators

The novel dual- and triple-passband bandpass filters are proposed in this paper. With the interdigital resonators embedded into the half-wavelength resonators, the bandpass filter with multiple passbands can be obtained easily. Moreover, by adopting the method of interdigital resonators, the passband with broader bandwidth on the higher frequency band can be obtained easily. Theoretical analyses are also described in this paper. The measured results of fabricated filters match well with the electromagnetic simulation; therefore, the feasibility of the proposed filters is approved.