Low-loss filtering switch by using dielectric waveguide resonators

A low-loss filtering switch by using the dielectric waveguide resonators (DWRs) is proposed. It is composed of a dielectric part and a printed circuit board (PCB) part, which are electrically connected by soldering. The filtering function is mainly implemented by the coupled DWRs and the switching function is realized on the PCB by simply changing the resonant frequency of the DWR. A fourth-order filtering switch, in which two DWRs are designed to be switchable, is designed for verification. When the PIN diodes are turned off, the filtering switch is on and an excellent bandpass response is obtained. No extra loss is caused by the off-state PIN diodes. When the PIN diodes are turned on, the resonant frequencies of the two switchable DWRs are moved away so that the filtering switch is off. Then, the designed filtering switch is fabricated and measured. The simulated and measured results exhibit excellent accordance. In on-state measurement, the passband is from 3.5 to 3.6 GHz and the in-band insertion loss is as low as 0.8 dB. Nevertheless, the proposed design owns much lighter weight since no metal cavity is used. In the off-state measurement, the isolation is better than 36 dB.