Design of dielectric resonator cavity filter with double-CT to control TZs

A new couple approach based on CT cross-coupling is proposed. Through changing size and location of the structure (U-type rod), while rotating the angle of the feeding probes which extended along ring dielectric resonators, transmission zeros (TZs) can be generated in high band or low band according to specific requirements. To prove the proposed idea, two six-order bandpass filters based on double-CT are designed and simulation. Good agreement is obtained between technique target and simulated results, showcasing good performance such as high out-of-band rejection and low return loss in the passband.