A Novel Reconfigurable Dual-Mode Microstrip Meander Loop Filter

A novel dual-mode reconfigurable band pass filter is proposed. A meander loop compact structure is used, where its four arms are brought inside the loop. Structure´s perturbation is designed by filling the gap between the two arms at the top right corner. The loop is loaded by four varactor diodes connected between each arm and a small square patch located at the centre. Varactors are shorted through a via at the centre of the small square patch to control the centre frequency of the filter. This structure is compact, simple in fabrication, and has a wide tuning range. A tunable bandpass filter is designed and implemented to tune over the range from 1.47 GHz to 2.40 GHz (relative tuneable bandwidth ~48%). The fractional bandwidth (FBW) changes from 6.9% at 2.4 GHz to 3.1% at 1.47 GHz.