Use of mutually inductive coupling in. probe design

An analysis is presented of mutually inductive coupling in probe design. it is assumed that near field couplings predominate and that lumped constants may therefore be employed. Using three published designs as examples, analytic techniques are presented for assessing B, field strength, losses, and signal-to-noise ratio in increasingly complex situations. The perturbing effect of the B, field from a matching coil is examined and it is shown that if the coil is too close to the sample there can be an asymmetry introduced in the rotating frame B, field. it is then shown that such asymmetries are potentially a general feature of inductively coupled, loaded coils. The importance of suppressing unwanted resonances is highlighted if tuning and matching are to be orthogonal, a potential advantage of mutually inductive matching. Finally, a lumped-constant simulation is briefly described for those situations where an analytic approach becomes too cumbersome. (C) 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 262-285, 2002*.