SUPERCONDUCTIVE TUNABLE FILTER WITH NARROW BAND AND BROAD TUNING RANGE

• US 3,818,390 A
• Filed: 04/12/1973
• Issued: 06/18/1974
• Est. Priority Date: 04/12/1973
• Status: Expired due to Term

• Current Assignee: Emanuel Gikow, John R. Vig
• Original Assignee: Emanuel Gikow, John R. Vig
• Inventors: Gikow, Emanuel, Vig, John R.
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Chatmon, Jr., Saxfield
• Application Number:
  US05/350,660
• Time in Patent Office: 432 Days
• Field of Search: 333/99S 334/65,66,67,68,41,69 331/17S
• US Class Current: 334/68
• CPC Class Codes: H03H 5/006 comprising simultaneously tunable inductance and capacitance
• CPC Class Codes: Y10S 505/866 Wave transmission line, network, waveguide, or microwave storage device

Abstract

A passive, high performance, superconductive LC loop tunable over a very broad tuning range and being capable of a high degree of rejection of undesired signals and wherein inductance and capacitance are adjustable to increase or decrease together by means of a common tuning element and wherein the tuning element has novel configuration for minimal distributed capacitance effect on the inductance to extend the upper frequency limit of the tuner and wherein input and output impedances are relatively constant over the tuning range.

Claims

1. A tunable resonant loop filter comprising:

an inductor that includes two cylindrical coaxial coextensive coils connected in series-aiding and providing a predetermined radial clearance between the coils, a cylindrical capacitor coaxial with said inductor and having one element that is axially spaced from and fixedly positioned relative to the inductor and having a unitary second element movable axially relative to the inductor and to the one capacitor element and having a circular conductor portion at one end for telescoping into the clearance between said two coaxial coextensive coils with a snug sliding fit and operable to reduce both capacitance And inductance in one direction of movement and operable to increase both capacitance and inductance in the other direction of movement, conductor means connecting said inductor and said capacitor as a closed loop, means for locating said second element selectively between two limits along the axis of said inductor and capacitor, in one of the two limits the second element being axially spaced from said one element and extending into the entire extent of clearance between the coils, whereby the capacitance between the two capacitor elements is essentially zero and the inductance of the inductor is minimum, in the other of the two limits the second element being axially spaced from the conductor and overlapping the entire axial length of the one capacitor element whereby capacitance between the capacitor elements is maximum and inductance of the inductor is maximum, and a pair of coupling coils substantially shorter than the inductor supported adjacent to and on opposite sides of the inductor with their axes substantially parallel to and coplanar with the inductor axis.

2. A tunable resonant loop filter as defined in claim 1 wherein the cylindrical portion at the one end of the second element includes a plurality of shorted conductor rings spaced apart axially and electrically isolated from each other, the axial length of the cylindrical portion supporting the shorted axial conductor rings being at least the axial length of said inductor, the remaining length of said second element being at least the axial length of the fixedly positioned capacitor element, the spacing between the inductor and the fixedly positioned capacitor element being such that when the second element completely overlaps the fixedly positioned element, the second element is axially spaced from the inductor, and when the cylindrical portion supporting the shorted rings is fully telescoped in the inductor and extends beyond both ends of the inductor, the second element is axially spaced from the fixedly positioned capacitor element.

3. A tunable resonant loop filter as defined in claim 2 wherein said means is mechanically joined to said coupling coils and is operable to rectilinearly displace said coupling coils together with said second element.

4. A tunable resonant loop filter as defined in claim 3 wherein said inductor coils, capacitor elements, conductor means and said coupling coils are of superconductor material, container means for providing a near zero degrees Kelvin ambiance, said inductor, capacitor, conductor means, and coupling coils being confined within said container means, said locating means extending through said container means and being selectively adjustable outside the container means.