Reconfigurable 4 pole bandstop filter based on RF-MEMS-loaded split ring resonators

A reconfigurable four-pole bandstop filter based on the combination of the split ring resonators (SRRs) and RF-MEMS switches, operative at the X frequency band, is presented for the first time. The fabricated device consists on a microstrip line loaded with four pairs of SRRs, exhibiting four different resonance frequencies, with two capacitive ON/OFF switches placed between the inner and outer ring of each SRR. Through their electrostatic actuation, the resonance frequency of each SRR can be shifted and as a result filter bandwidth can be digitally controlled, or even suppressed. Good agreement between theory and experiment is achieved.