Absolute Calibration of the Magnetic Field Generated by a Small Coil

A technique is discussed which provides the coil constant, i.e., generated field per increment of applied current, for small-coil systems or solenoids in terms of absolute units traceable to the National Bureau of Standards. Essentially, the procedure involves the use of the coil system under test to cancel the geomagnetic field vector and measurement of the applied current. Under proper conditions, an absolute accuracy to within 0.02 percent or better is obtainable.