A Fully Tunable Filter with Wide Range Notch Frequency Tuning and Bandwidth Switchable

Abstract

A compact wideband fully tunable filter is designed based on a quarter-mode integrated waveguide resonator. With only two varactor diodes at the port gap, the notch frequency can be tuned continuously in the entire passband range, and the interference signal in the band can be flexibly suppressed. In addition, by controlling the on and off of two PIN diodes, switching between the two bandwidths of 1.7 GHz and 3.3 GHz is achieved without affecting the notch frequency tuning in the bandwidth. The notch frequency tuning range is 4 GHz to 6.4 GHz. The insertion loss at the notch frequency is -15dB to -30dB, which is sufficient to eliminate in-band noise.