Patent ID: 6384603
Filing Date: 2002-05-07
Classification: G01R

Abstract:
A quadrature radio frequency field coil for use in a unidirectional magnetic field for effecting magnetic resonance experiments on a sample comprising:a first annular conductor lying generally in a first plane at a first end of the coil; a second annular conductor lying generally in a second plane at a second end of the coil; the first and second planes being parallel and spaced so as to define a hollow interior of the coil into which the sample can be received; the first annular conductor including at least one first capacitor connected therein in series; the second annular conductor including at least one second capacitor connected therein in series; the first and second annular conductors and the first and second capacitors being arranged such that, in a first mode, current can be caused to flow therein to generate a first oscillating radio frequency field, which is substantially homogeneous within the hollow interior, at a resonant frequency dependent upon the shape and impedance of the first and second annular conductors and the mutual inductance therebetween; a first plate conductor having a length extending across the annular conductors generally at right angles to the first and second planes so as to bridge the space therebetween; a second plate conductor having a length extending across the annular conductors generally at right angles to the first and second planes so as to bridge the space therebetween; the first and second plate conductors being arranged at diametrically opposed locations on the annular conductors and being generally parallel so as to be located on opposite sides of the hollow interior; the plate conductors being arranged such that, in a second mode, current can be caused to flow in a circuit along the first plate conductor, through the first annular conductor to the second plate conductor, along the second plate conductor and through the second annular conductor to the first plate conductor; the circuit including at least one third capacitor; the circuit and the third capacitor being arranged to generate a second oscillating radio frequency field, at a resonant frequency dependent upon the shape and impedance of the first and second plate conductors and the annular rings; the plate conductors having a width transverse to the length thereof which is sufficient to cause the second field to be substantially homogeneous within the hollow interior; the first and second annular conductors and the first and second plate conductors being shaped and arranged and the first, second and third capacitors being arranged such that the first and second fields have the same resonant frequency and such that the first and second fields are substantially mutually orthogonal and arranged for co-operation with a main magnetic field perpendicular to the plane of the plate conductors.