Dual-band coupled-line bandpass filter with independently tunable bandwidths

摘要

This paper reports a novel dual-band coupled-line bandpass filter. Comprising a quadruple-mode coupled-line resonator, this proposed filter could filter signals on two frequency bands. After introducing two varactors, one of the four resonances could be continuously altered by changing the capacitance of the varactors, thus the two frequency bandwidths could be independently tunned. In this paper, the detailed explanation for its operation is given, and the agreement between the expected and practical performance sufficiently confirms the robustness and effectiveness of this proposed filter.