Patent ID: 8159314

Claim:
An actively tuned filter, comprising: first and second electromagnetically coupled coiled resonators, each of the first and second coiled resonators having an open end configured to receive an input and a shorted end configured to connect the corresponding first or second coiled resonator to a ground; and a plurality of variable capacitances, each of the variable capacitances including one or more capacitors allowing selection of a capacitance to be applied to the first and second coiled resonators, each variable capacitance being connected to the shorted end of the first or second coiled resonators, wherein each of the one or more capacitors of each of the variable capacitances is series coupled to an inductor, wherein each inductor is coupled to ground, wherein the first coiled resonator and the second coiled resonator are arranged in an end-to-end configuration, wherein an axis of the first coiled resonator and an axis of the second coiled resonator are aligned along a single longitudinal axis, wherein one or more coils of the first and second coiled resonators are circumferential to the single longitudinal axis.