An assembly of resistive paper and liquid crystal sheet, conveniently and cheaply constructed for visual detection of the electric fields associated with an rf probe, is presented. Electrical asymmetries, and “hot‐spots” usually associated with conservative electric fields, are easily visualized by the color patterns displayed. The device is of considerable assistance in probe design and the minimization of dielectric loss. Copyright © 1993 Wiley‐Liss, Inc., A Wiley Company