Solenoidal array coils.

New concepts are presented for inherent decoupling of multi-element solenoidal arrays. First, an uneven counter-rotational (UCR) coil is reported in which two counter-rotational sections are wound unevenly, resulting in a quasi-one-peak sensitivity profile with a null-B1 point. Adding a second solenoid element near the null-B1 point forms an inherently-decoupled solenoidal array. Unlike a sandwiched solenoidal array, an UCR solenoidal array allows for signal contribution at the center from both solenoid elements. Second, a double counter-rotational (DCR) coil is presented in which two null-B1 points are formed by having one counter-rotational winding on each side of the coil. Two solenoidal elements can be added to form a solenoidal array. Finally, more solenoid elements can be added to the array provided that the added coil elements are DCR elements. These DCR coil elements can be used as building blocks for more complex solenoidal arrays. These concepts are illustrated using numerical simulations and tested using prototype coils. Copyright 2002 Wiley-Liss, Inc.