Dual-Band Bandpass Filter With Large Frequency Ratio And Independently Tunable Center Frequencies

For the first time, a dual-band bandpass filter with independently tunable center frequencies was implemented to support microwave and millimeter-wave frequency bands simultaneously. To achieve the desired high-frequency ratio, the micro-strip element is combined with the metallic cavity element through the aperture coupling mechanism. Meanwhile, the proposed approach allows the independent control of the two operating frequencies. For demonstration, a tunable dual-band bandpass filter was designed, fabricated and measured. A maximum tunable frequency ratio up to 24 can be achieved together with the independent center frequency tunability.