RF MEMS hairpin filter with three reconfigurable bandwidth states

An approach to bandwidth-reconfigurable planar filter is proposed. RF MEMS switches are used to modify the inter-resonator coupling in hairpin band pass filters so as to control the bandwidth while keeping constant the centre frequency and return loss. The design and full-wave simulation of a 4^th-order hairpin-line filter with 3 bandwidth states is reported to demonstrate the feasibility of the proposed approach. Measurements carried out with hardwire connections showed a good agreement with the predicted results.