US4439733A — Distributed phase RF coil

Claim 1

Independent Claim 148 words

In a system for generating and detecting magnetic resonance in materials placed in the system for examination, the system having a magnet for providing a static magnetic field directed along a line or axis, the system generating magnetic resonance in the materials through their exposure to a radio-frequency magnetic field having components transverse to the axis, improved apparatus for generating or detecting the radio-frequency magnetic field, the improvement comprising: (a) a plurality of conductive elements positioned in spaced relation about the axis; (b) means for causing alternating currents to flow in the conductive elements; and (c) means for setting the relative amplitudes of the currents in each of the conductive elements, there being at least one set of current amplitudes, generally different from one another and alternating at a radio frequency, which is able to generate a composite magnetic field transverse to the axis that is substantially uniform.

Claim 2

Dependent Claim 148 words

In a system for generating and detecting magnetic resonance in materials placed in the system for examination, the system having a magnet for providing a static magnetic field directed along a line or axis, the system generating magnetic resonance in the materials through their exposure to a radio-frequency magnetic field having components transverse to the axis, improved apparatus for generating or detecting the radio-frequency magnetic field, the improvement comprising: (a) a plurality of conductive elements positioned in spaced relation about the axis; (b) means for causing alternating currents to flow in the conductive elements; and (c) means for setting the relative amplitudes of the currents in each of the conductive elements, there being at least one set of current amplitudes, generally different from one another and alternating at a radio frequency, which is able to generate a composite magnetic field transverse to the axis that is substantially uniform.

Claim 3

Dependent Claim 50 words

Apparatus according to claim 1, wherein the means for setting the relative amplitudes of the currents comprises means for controlling the amplitudes of the currents in the conductors relative to one another and for controlling such amplitudes in relation to the positions of the respective conductive elements about the axis.

Claim 4

Dependent Claim 55 words

Apparatus according to claim 2, wherein the means for setting the relative amplitudes of the currents comprises means for interconnecting the conductive elements, the interconnecting means and the conductive elements together forming an electrical closed-loop, the electrical closed-loop sustaining a standing wave when coupled to a source of electrical energy oscillating at the radio frequency.

Claim 5

Dependent Claim 41 words

Apparatus according to claim 3, wherein the interconnecting means comprises means for causing the amplitudes of the currents in the interconnected conductive elements to differ when the apparatus is coupled to a source of electrical energy oscillating at the radio frequency.

Claim 6

Dependent Claim 48 words

Apparatus according to claim 4, wherein, when the apparatus is coupled to a source of electrical energy oscillating at the radio frequency to sustain the standing wave, the sum of the phase-angle differences across the conductive elements and the phase-angle differences across the interconnecting sections total 2π radians.

Claim 7

Dependent Claim 38 words

Apparatus according to claim 5, wherein the means for setting the relative amplitudes of the currents in the interconnected conductive elements comprises sections of transmission line, the sections of transmission line separating the conductive elements from one another.

Claim 8

Dependent Claim 38 words

Apparatus according to claim 6, wherein the sections of transmission line include means for limiting interaction of magnetic fields associated with currents in the sections of transmission line with magnetic fields associated with currents in the conductive elements.

Claim 9

Dependent Claim 69 words

Apparatus according to claim 6, wherein the sections of transmission line include an inner conductor and an outer conductor, the inner conductor being integral with the conductive elements of the apparatus, and the outer conductors of the sections of transmission line being spaced from the inner conductor and substantially confining magnetic fields associated with currents in the transmission line sections to the region between the inner and outer conductors.

Claim 10

Dependent Claim 14 words

Apparatus according to claim 7, wherein the conductive elements define a surface of revolution.

Claim 11

Dependent Claim 13 words

Apparatus according to claim 7, wherein the conductive elements define a cylindrical surface.

Claim 12

Dependent Claim 18 words

Apparatus according to claim 10, wherein the conductive elements are substantially parallel with the axis of the cylinder.

Claim 13

Dependent Claim 19 words

Apparatus according to claim 10, wherein the conductive elements are skewed with respect to the axis of the cylinder.

Claim 14

Dependent Claim 123 words

A coil assembly for either exciting a material undergoing magnetic resonance analysis with the use of an oscillating radio-frequency magnetic field or for detecting such magnetic fields as a result of the magnetic resonance of such material, the coil assembly comprising: (a) a coil support defining a region within the support in which a material to be examined may be placed; and (b) a substantially toroidally-shaped coil peripherally positioned about the coil support, the coil having alternating sections of conductive elements separated by sections of coaxial transmission line, the conductive elements being the center conductor of the sections of coaxial transmission line, and the conductive elements between the sections of coaxial transmission line being substantially parallel to the axis of the coil support.

Claim 15

Dependent Claim 123 words

A coil assembly for either exciting a material undergoing magnetic resonance analysis with the use of an oscillating radio-frequency magnetic field or for detecting such magnetic fields as a result of the magnetic resonance of such material, the coil assembly comprising: (a) a coil support defining a region within the support in which a material to be examined may be placed; and (b) a substantially toroidally-shaped coil peripherally positioned about the coil support, the coil having alternating sections of conductive elements separated by sections of coaxial transmission line, the conductive elements being the center conductor of the sections of coaxial transmission line, and the conductive elements between the sections of coaxial transmission line being substantially parallel to the axis of the coil support.

Claim 16

Dependent Claim 37 words

A coil assembly according to claim 13, which further comprises a pair of end shields and a cylindrically-shaped conductive sheet interconnecting the end shields, the toroidally-shaped coil being enclosed by the end shield and the conductive sheet.

Claim 17

Dependent Claim 27 words

A coil assembly according to claim 14, which further comprises means for inductively coupling radio-frequency electrical energy to one of the conductive elements of the toroidally-shaped coil.

Claim 18

Dependent Claim 30 words

A coil assembly according to claim 15, wherein the means for coupling the radio-frequency energy comprises a conductor positioned parallel to one of the conductive elements of the toroidally-shaped coil.

Claim 19

Dependent Claim 21 words

A coil assembly according to claim 14, wherein the toroidally-shaped coil makes one revolution about the axis of the coil support.

Claim 20

Dependent Claim 20 words

A coil assembly according to claim 17, wherein the toroidally-shaped coil has a conductor which forms an electrical closed loop.

Claim 21

Dependent Claim 49 words

A coil assembly according to claim 13, wherein sections of coaxial transmission line interconnect corresponding ends of conductive elements separated by angular positions about the axis, the separation being equal in radians to 2π plus or minus the quantity 2π divided by the number of conductive elements thus interconnected.

Claim 22

Dependent Claim 29 words

A coil assembly according to claim 13, wherein the sections of coaxial transmission line interconnect opposite ends of adjacent conductive elements positioned about the axis of the coil support.

Claim 23

Dependent Claim 27 words

A coil assembly according to either of claims 19 or 20, wherein the conductive elements are equally-spaced from one another about the axis of the coil support.

Claim 24

Dependent Claim 64 words

A coil assembly according to claim 13, wherein the sections of transmission line are of such length, and the conductive elements are positioned about the axis of the coil support, such that an oscillating magnetic field transverse to the axis exists when the coil assembly is excited by an RF electrical signal having a wavelength in the coil assembly equal to its electrical length.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1987-03-27	1987-09-26	1988-03-27	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1991-03-27	1991-09-26	1992-03-27	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1995-03-27	1995-09-26	1996-03-27	$7700.00	Window Closed / Lapsed

Distributed phase RF coil

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