A superconducting tunable filter comprises a dielectric base plate; a
patch-shaped resonator pattern formed of a superconducting material on
the dielectric base plate; a top dielectric locally placed on the
superconducting resonator pattern at a prescribed position and made of a
material with an electric-field dependent permittivity; a conducting
pattern formed on a top face of the top dielectric; and a bias voltage
supply configured to apply a bias voltage between the conducting pattern
and the superconducting resonator pattern.