A Double Discrete Cosine Quadrature Coil Design

Abstract

A design for a simple, multiply tunable, high-field quadrature NMR coil is presented. The new quadrature design is achieved by combining the fields from two linear B 1 field discrete cosine coils at 90° in both space and time. This design has been termed the double discrete cosine quadrature coil. Calculations and measurements indicate that for a single-tuned version of the double discrete cosine quadrature coil, which requires only two tuning capacitors, nearly the complete quadrature advantage may be obtained. For the double-tuned version of the double discrete cosine quadrature coil, which requires only four tuning capacitors, calculations and measurements confirm that roughly 96% of the quadrature advantage is obtained at the lower operating frequency and roughly 80% of the quadrature advantage is obtained at the higher operating frequency, under both extreme filling and extreme loading conditions.