A dual-band switchable bandpass filter using connected-coupling mechanisms

In this paper, a dual-band switchable bandpass filter using switchable connected-coupling lines is presented. The switchable connected-coupling line is formed by embedding a RF traveling-wave switch into a connected-coupling line. In thru state, the switchable connected-coupling line serves as an admittance inverter to provide adequate coupling for a bandpass response. In isolated state, the switchable line acts as a RF switch to cut off the coupling path to achieve a high isolation. A switchable dual-band filter operating at 1.5 and 2.5 GHz was designed and fabricated to validate the design concept.