US4952879A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic resonance apparatus with uncoupled RF coils
Assignee: US Philips Corp
•
Filing: 1989-04-14
•
Granted: 1990-08-28
•
Expires: 2009-04-14
Abstract
Abstract In a magnetic resonance apparatus coils of an rf coil system are incorporated for detection of magnetic resonant signals at mutually different frequencies in resonant circuits having a zero impedance for the natural frequency and an infinite impedance for a given deviating frequency. In the switching circuits a coaxial cable is used having a length which has a reactance in parallel with a second reactance to form a tuned circuit adapted to the desired frequency.
Inventors
- 👤 Johannes J. Van Vaals
- 👤 Anthonie H. Bergman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 01:49
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/32; G01R33/36; G01R33/3628; G01R33/3635
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
124 words
A magnetic resonance apparatus having a magnet system for generating a stationary magnetic field in the measuring space, a coil system for generating gradient fields in the measuring space and comprising an rf coil system for excitation and detection of magnetic resonant signals, characterized in that a coil of the rf coil system to be uncoupled is incorporated in a resonant circuit having substantial zero impedance for a resonant frequency and substantial infinite impedance for a frequency deviating therefrom of a coil to be uncoupled therefrom, said resonant circuit comprising a coaxial cable forming a reactive impedance connected in parallel to the rf coil and having an adjustable reactive impedance connected in parallel thereto forming a tuned circuit therewith in parallel to said coil.
Claim 2
Dependent Claim
124 words
A magnetic resonance apparatus having a magnet system for generating a stationary magnetic field in the measuring space, a coil system for generating gradient fields in the measuring space and comprising an rf coil system for excitation and detection of magnetic resonant signals, characterized in that a coil of the rf coil system to be uncoupled is incorporated in a resonant circuit having substantial zero impedance for a resonant frequency and substantial infinite impedance for a frequency deviating therefrom of a coil to be uncoupled therefrom, said resonant circuit comprising a coaxial cable forming a reactive impedance connected in parallel to the rf coil and having an adjustable reactive impedance connected in parallel thereto forming a tuned circuit therewith in parallel to said coil.
Claim 3
Dependent Claim
27 words
A magnetic resonance apparatus as claimed in claim 1, characterized in that the coaxial cable has an open end and the parallel-arranged impedance is an adjustable inductance.
Claim 4
Dependent Claim
35 words
A magnetic resonance apparatus as claimed in claim 1, characterized in that the coaxial cable has an open end and the parallel-arranged impedance is a parallel arrangement of a fixed inductance and a variable capacitor.
Claim 5
Dependent Claim
27 words
A magnetic resonance apparatus as claimed in claim 1, characterized in that the coaxial cable has a short-circuited end and the parallel-arranged impedance constitutes an adjustable capacity.
Claim 6
Dependent Claim
31 words
A magnetic resonance apparatus as claimed in claim 1 where said cable is dimensioned n/2λ<L<(n/2+1/4)λ, where L is the length of the cable and n is an odd interger or 0.
References Cited (Backward Citations)
US4129822A
Cited
US4700137A
Cited
US4712069A
Cited
US4691164A
Cited
US4739269A
Cited
US4816765A
Cited
US4812764A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-27 | 1994-02-26 | 1994-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-27 | 1998-02-26 | 1998-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-27 | 2002-02-26 | 2002-08-28 | $7700.00 | Window Closed / Lapsed |