Nuclear magnetic resonance transmitter and receiver system
First Claim
1. A tuning circuit for a nuclear magnetic resonance transmitter and receiver system for sensing and coupling an NMR signal to a preamplifier comprising:
- a pick-up coil,a first capacitive element (18) connected in parallel with said pick-up coil, the capacitance of which is associated with a shielded connection means for transferring the NMR signal detected at said pick-up coil to said preamplifier, anda second capacitive element (20) connected to said coil for forming a resonant circuit in combination with said pick-up coil,wherein the respective values of said capacitive elements are such that the following condition applies
space="preserve" listing-type="equation">1/C1+1/Ct= constantwhere Ct is the total capacitance of the first capacitive element and the stray capacitance of the connection means and C1 is the capacitance of said second capacitive element.
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Accused Products
Abstract
A tuning circuit for an NMR transmitter and receiver system includes a variable and fixed capacitor connected to a pick-up coil. Matching of the pick-up coil to a preamplifier is associated with matching to available cable impedance. As a consequence of the impedance matching, the resonance tuning is carried out by adjustment of the variable capacitor. In utilizing the tuning circuit, a high Q of pick-up coil is obtained and the detected NMR signal is optimally transferred to the preamplifier while the length of the cable connecting the coil with the preamplifier is not limited.
52 Citations
8 Claims
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1. A tuning circuit for a nuclear magnetic resonance transmitter and receiver system for sensing and coupling an NMR signal to a preamplifier comprising:
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a pick-up coil, a first capacitive element (18) connected in parallel with said pick-up coil, the capacitance of which is associated with a shielded connection means for transferring the NMR signal detected at said pick-up coil to said preamplifier, and a second capacitive element (20) connected to said coil for forming a resonant circuit in combination with said pick-up coil, wherein the respective values of said capacitive elements are such that the following condition applies
space="preserve" listing-type="equation">1/C1+1/Ct= constantwhere Ct is the total capacitance of the first capacitive element and the stray capacitance of the connection means and C1 is the capacitance of said second capacitive element. - View Dependent Claims (2, 3, 4, 5)
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6. A tuning circuit for sensing and coupling an NMR signal to a preamplifier comprising:
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(a) a pick-up coil, (b) a first capacitive element having a first side thereof connected to one end of said pick-up coil and to a central signal wire of a coaxial cable, (c) a second side of said first capacitive element connected to a shielded conductor of said coaxial cable, (d) a second capacitive element having a first side thereof electrically connected to said second side of said first capacitive element, (e) a second side of said second capacitive element electrically connected to the other end of said pick-up coil, and (f) said first and second capacitive elements selected such that;
space="preserve" listing-type="equation">1/C1+1/Ct=constant
space="preserve" listing-type="equation">LCcw.sup.2 =1where
space="preserve" listing-type="equation">Cc=1/C1+1/CtL=the inductance of said pick-up coil, w=the resonant frequency of the tuning circuit, Ct=the combined capacitance of said first capacitive element and the stray capacitance of said cable. - View Dependent Claims (7, 8)
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Specification