Quadrature RF field coil for use in magnetic resonance

There is described a quadrature radio frequency (RF) coil design to be used with appropriate magnetic resonance imaging (MRI) hardware to obtain images of the human body. The design provides good RF field homogeneity over a volume suitable for thoracic diagnostic imaging, and operates in quadrature mode as a transmit and/or receive coil. The design is for use with a 0.33 tesla permanent, C shaped magnet with a vertical main field but is of general applicability. The coil includes two parallel annular coils connected at top and bottom by two plate conductors. The plates are split longitudinally and transversely and connected across the splits by capacitors to define two modes of resonant oscillation which can be tuned separately and independently to the same frequency, where the modes define fields which are mutually orthogonal. The fields are at right angles to the magnetic field and to the plate conductors so that the sample can be inserted through the openings at right angles to the plates.