Frequency selector using voltage-sensitive capacitors for tuning and bandwidth control

Claim 1

A MULTIPLE TUNED REACTANCE FILTER COMPRISING: A PLURALITY OF TUNED TANK CIRCUITS, EACH OF SAID TUNED TANK CIRCUITS INCORPORATING A VARIABLE REACTANCE DEVICE; A REACTIVE COUPLING NETWORK BETWEEN EACH OF SAID TANK CIRCUITS FOR COUPLING SAID TANK CIRCUITS IN TANDEM, EACH OF SAID COUPLING NETWORKS INCLUDING A VARIABLE REACTANCE DEVICE; A REACTIVE VOLTAGE DIVIDER CONNECTED ACROSS THE FIRST OF SAID TANK CIRCUITS IN SAID FILTER, SAID VOLTAGE DIVIDER INCLUDING ANOTHER OF SAID VARIABLE REACTIVE IMPEDANCE DEVICES IN SERIES WITH A FIXED REACTIVE DEVICE, EACH OF SAID VARIABLE REACTANCE DEVICES IN SAID TANK CIRCUITS, SAID COUPLING NETWORK AND SAID VOLTAGE DIVIDER HAVING CHARACTERISTICS SUCH THAT ITS REACTIVE IMPEDANCE VARIES AS A FUNCTION OF APPLIED DIRECT VOLTAGE; MEANS CONNECTING A VARIABLE DIRECT CURRENT SOURCE OF VOLTAGE TO EACH OF SAID VARIABLE REACTANCE DEVICES FOR SIMULTANEOUSLY INCREASING OR DECREASING THE REACTANCE OF SAID DEVICES WHEREBY THE RESONANT FREQUENCY OF SAID FILTER IS ADJUSTED WHILE THE BAND PASS OF SAID FILTER REMAINS SUBSTANTIALLY CONSTANT, AND WHEREBY THE REACTIVE IMPEDANCE OF SAID VOLTAGE DIVIDER IS ADJUSTED TO MAINTAIN A RELATIVELY CONSTANT INPUT IMPEDANCE FOR SAID FILTER AS THE RESONANT FREQUENCY IS ADJUSTED.