John H Claassen

US Patent:

6501971, Dec 31, 2002

Filed:

Oct 30, 1996

Appl. No.:

08/739981

Inventors:

Stuart A. Wolf - Bowie MD
Frederic J. Rachford - Washington DC
John Claassen - Washington DC

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

H01P 1218

US Classification:

505210, 333204, 3332192, 333235

Abstract:

A magnetic ferrite microwave resonator frequency tunable filter and method for tuning a filter having both a resonator portion and a tuning portion. The resonator portion has an input for receiving an electromagnetic signal and an output for emitting an electromagnetic signal. A tuning portion includes a magnetic ferrite element disposed in first and second magnetic fields generated by a fixed magnet and an electromagnet. The magnetic ferrite element has a magnetic permeability determined by the first and second magnetic fields. The first magnetic field places a ferromagnetic resonance frequency of the ferrite element near a frequency of the electromagnetic signal transmitted by the resonator portion. The second magnetic field is variable in response to a varying current supplied to the electromagnet to change the permeability of the ferrite element, to thereby alter the center frequency of the resonator, thereby facilitating tuning of the electromagnetic signal.

US Patent:

20110152102, Jun 23, 2011

Filed:

Dec 22, 2009

Appl. No.:

12/644194

Inventors:

JOHN H CLAASSEN - Washington DC, US

International Classification:

H01L 39/02
H01B 12/00
H01L 39/24
H02H 7/00
H01L 39/12

US Classification:

505160, 505230, 505433, 361 19, 29599

Abstract:

An apparatus, system and method for measuring electrical dissipation in a coil wound with superconducting wire or tape are disclosed. The superconducting coil may include one or more superconducting wires wound together with a witness winding. The one or more superconducting wires may be electrically connected to the witness winding. The one or more superconducting wires may be shaped as a tape. The witness winding may be a tape. The superconducting coil may be wound into a flat pancake structure. The witness winding may be configured to detect a quench in the one or more superconducting wires, which may otherwise interfere with the superconductivity of the one or more superconducting wires.