A novel balanced bandpass reconfigurable microstrip filter is presented, where in differential mode, the filter operates in seven different bands, and each inductor LM represents a state of frequency. The common mode rejection ration (CMRR) is better than 30 dB for all the states. The central frequency of the filter is changed by liquid metal droplets flowing along a microfluidic channel placed at the middle of the inductors LM. For demonstration, a third-order filter is designed, simulated, and fabricated, operating in the S-band. Good agreement between simulation and measurement is presented.
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