Apparatus for dynamically disabling an NMR field coil
US4833409A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 21, 1987 |
| Grant date | May 23, 1989 |
| Priority date | — |
| Expiry date | Dec 21, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/3628
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A detunable coil assembly for an NMR imaging system has a cylindrical cage coil comprising two spaced-apart conductive end loops with a plurality of conductive segments extending between the loops. A grounded shield is disposed around the cage coil. Each of the end loops is coupled to the shield by four switchable impedance circuits that are equidistantly spaced around the loop. Each impedance means includes a coaxial cable having a length equal to one-quarter the wavelength of the resonant frequency of the cage coil with the central conductor coupled at one end to the cage coil and the other conductor connected to the shield. A PIN diode terminates the other end of the coaxial cable. A voltage supply provides potentials for alternately forward and reverse biasing the PIN diode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.