Multi-channel balun for magnetic resonance apparatus
US6320385A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 17, 1999 |
| Grant date | Nov 20, 2001 |
| Priority date | — |
| Expiry date | Sep 17, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/3657
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A multi-channel balun (70, 72) blocks stray RF current from flowing on shield conductors of coaxial RF cables of a magnetic resonance apparatus. The balun comprises a parallel combination of an even number of helical coils of shielded transmission cable (L10, L12; L14, L16, L18, L20) wound in alternate directions such that voltages iduced by their external RF fields cancel. One capacitor (C10; C16, C18) is connected in parallel symmetrically with each pair of helical coils, with trim capacitors (C12; C22) fixed in the coil plug (86, 90) to retune the balun as required. The multi-channel balun (70, 72) accommodates magnetic resonance systems with an odd or even number of channels without requiring shielding. Preferably, the balun (70, 72) is constructed on a single circuit board in a close-packed relationship that is compact and space efficient, yet provides better decoupling from the transmit field.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.