Tunable signal coupler for a magnetic resonance imaging system
AssigneeGeneral Electric Company
InventorDavid E. Lyle
Life of this patent
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Abstract
A device for coupling a radio frequency transceiver of an MRI system utilizes a tunable hybrid network. The network is formed of fixed value capacitors connected to transmission lines that provide inductive reactance to the network. The connection of the components is such that an input signal applied to one node produces a pair of signals in quadrature at two other nodes. In order to insure that the pair of signals have the proper phase and amplitude relationship a fixed capacitor is connected across specific pairs of the transmission lines. The point of connection of that capacitor to the transmission lines is chosen to properly tune the network.
Claims16
A circuit for coupling a transmitter of a magnetic resonance imaging system to an antenna, said circuit comprising:
- first and second transmission lines with each transmission line having two ends;
- a first capacitor connected across first ends of said first and second transmission lines;
- a first conductor for coupling a signal at a given radio frequency from the transmitter to the first end of said first transmission line;
- a second capacitor connected across said first and second transmission lines at an intermediate point between the ends of each transmission line, the point being chosen to tune the circuit to the given radio frequency;
- and
- a second conductor for connecting the antenna to an end of the second transmission line.
The circuit as recited in claim 3 wherein said second conductor connects the antenna to a second end of said second transmission line that is remote from the first end.
The circuit as recited in claim 4 further comprising a fourth conductor for connecting a receiver to the first end of said second transmission line.
A circuit for coupling a transceiver of a magnetic resonance imaging system to an antenna, said circuit comprising:
- first, second, third and fourth capacitors connected serially in a ring having nodes between adjacent capacitors
- first, second, third and fourth transmission lines each having a first end connected to a different node and a second end to which a fixed electrical potential is applied;
- a first conductor for coupling a signal at a given radio frequency from the transceiver to the node between the first and fourth capacitors;
- conductive elements for connecting the antenna to the node between the first and second capacitors and to the node between the second and third capacitors;
- a second conductor for connecting a receiver section of the transceiver to the node between the third and fourth capacitors;
- a first tuning capacitor connected across said first and second transmission lines at intermediate points between the ends of those transmission lines, the points being chosen to tune the circuit to the given radio frequency;
- and
- a second tuning capacitor connected across said third and fourth transmission lines at intermediate points between the ends of those transmission lines, the points being chosen to tune the circuit to the given radio frequency.
Dependencies are inferred from the claim text.