Compact reconfigurable bandpass filter with wide frequency tuning range

摘要

A compact reconfigurable bandpass filter with wide tuning range is proposed in this letter. The reconfigurable function is realized by utilizing two varactor diodes at the end of the bandpass filter. Instead of using the coupling gap to create the desired coupling coefficients, a high characteristic impedance line is applied. A compact reconfigurable filter is designed, fabricated and measured. The measured tuning frequency ranges from 0.38 GHz to 0.96 GHz, which is about 86.6% of the central frequency. The measured insertion loss of the proposed reconfigurable filter is less than 2.5 dB, while the measured return loss is greater than 11 dB.