Fully Reconfigurable Filter Based on a Microstrip Patch Resonator with Low-Voltage Driving

An approach to bandwidth- and frequency-reconfigurable planar filters is proposed. Switching elements are used in a modified dual-mode microstrip resonator to independently tune the centre frequency (up to 10 %) and the
bandwidth (4%) of the filter. In order to demonstrate the feasibility of the proposed approach the design of a 2nd-order tunable filter is presented along with simulation and measurement results. Measurement results showed an average Insertion Loss (IL) of 2dB and return loss better than 12 dB. Bandwidth and frequency tuning range are 4% and 10% respectively as simulated.