A compact tunable bandpass filter with tunable transmission zeros in the pass band adopting a nested open ring resonator

Abstract

In order to suppress the high level interference signals in the passband of a wideband communication system, a tunable bandpass filter with tunable transmission zeros in the pass band is presented in this letter. The tunable nested open ring resonator is operated to achieve the tunable transmission zeros in the tunable pass band. Adopting the nested open ring resonators, the passband and the transmission zeros can also be designed according to the demand independently. A tunable bandpass filter adopting five nested open ring resonators is designed, fabricated and measured. The tunable filter is tuning in the range of 400‐530 MHz. The 3 dB bandwidth of the tunable filter is in the range of 17‐18 MHz. The simulated results are in good agreement with the measured ones.

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