NMR probe circuit with nodal impedance bridge
First Claim
1. A nuclear magnetic resonance probe circuit comprising:
- an inductive sample coil resonant at a frequency f1;
a resonator circuit electrically connected to the sample coil, the resonator circuit having a plurality of points of electric field minima for an RF signal at the frequency f1;
a input port connected to a one of said minima points via which an electrical signal at a frequency f2 is input to the resonator circuit; and
an impedance connected between the two of said minima points that significantly modifies the frequency response of the probe circuit at frequency f2, but has a negligible effect on the frequency response of the probe circuit at frequency f1.
1 Assignment
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Accused Products
Abstract
A nuclear magnetic resonance (NMR) probe circuit is used with a sample coil tuned to a primary frequency f1. The circuit is arranged to have a plurality of points of electric field minima at the f1 frequency. One or more additional frequencies may be coupled to the circuit at these points, without interaction with f1. The probe circuit also uses an impedance coupled between two of the minima points that affects the frequency response at the additional frequency or frequencies, without affecting the frequency response at f1. The impedance may be made adjustable to allow tuning of the relative frequency resonances.
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Citations
20 Claims
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1. A nuclear magnetic resonance probe circuit comprising:
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an inductive sample coil resonant at a frequency f1;
a resonator circuit electrically connected to the sample coil, the resonator circuit having a plurality of points of electric field minima for an RF signal at the frequency f1;
a input port connected to a one of said minima points via which an electrical signal at a frequency f2 is input to the resonator circuit; and
an impedance connected between the two of said minima points that significantly modifies the frequency response of the probe circuit at frequency f2, but has a negligible effect on the frequency response of the probe circuit at frequency f1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A nuclear magnetic resonance probe circuit comprising:
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an inductive sample coil resonant at a frequency f1;
a resonator circuit electrically connected to the sample coil and balanced so that a point of electric field minimum is located at a center of the sample coil, the resonator circuit comprising a plurality of transmission lines and having a plurality of additional points of electric field minima for an RF signal at the frequency f1;
a first input port connected to a first one of said minima points via which an electrical signal at a frequency f2 is input to the resonator circuit;
a second input port connected to a second one of said minima points via which an electrical signal at a frequency f3 is input to the resonator circuit; and
an impedance connected between the first and second minima points that significantly modifies the frequency response of the probe circuit at frequencies f2 and f3, but has a negligible effect on the frequency response of the probe circuit at frequency f1.
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13. A method of producing a nuclear magnetic resonance probe circuit having an inductive sample coil resonant at a frequency f1 and a resonator circuit electrically connected to the sample coil, the resonator circuit having a plurality of points of electric field minima for an RF signal at the frequency f1, the method comprising:
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coupling a signal at frequency f1 to the resonator circuit at a point away from said minima points;
coupling a signal at a frequency f2 to the resonator circuit at one of said minima points; and
providing an impedance connected between two of said minima points that significantly modifies the frequency response of the probe circuit at frequency f2, but has a negligible effect on the frequency response of the probe circuit at frequency f1. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification