Dual‐band bandpass to bandstop switchable filter with independently tunable center frequency and bandwidth

Abstract

AbstractThis article presents a dual‐band bandpass (BP) to bandstop (BS) switchable filter with independently tunable center frequency and bandwidth. Two different length half‐wavelength resonators are coupled with two separate coupling lines. Each resonator consists of a varactor‐loaded stub at the center to tune the even mode frequencies, whereas two identical varactors are connected at the ends to tune odd and even mode frequencies simultaneously. The center frequency of the first passband is tuned from 1.03 to 1.4 GHz with constant fractional bandwidth (CFBW) of 3.4%, and second passband from 1.35 to 1.74 GHz with CFBW of 2%. BP to BS switching is achieved by connecting a p‐i‐n diode between input and output feedlines.