Electromechanically tunable filter with impedance step

New principle of microstrip resonator and filter tuning is developed and studied. Realized idea is the operation by substrate effective dielectric constant (epsiv_eff) piezo-controlling. Narrow air gap (Delta) is created between substrate and ground electrode, and the piezoelectric plate controls its size. The changing of epsiv_eff(Delta) leads to the variation of filter resonant frequency