Three directional Helmholtz coils for a low frequency-magnetic-field immunity test

A magnetic field inside a space surrounding three sets of Helmholtz coils is studied to propose a new radiated immunity test method. The proposed immunity test set arranges the Helmholtz coils three dimensionally and is able to generate the magnetic field of arbitrary direction. Therefore the immunity characteristics of equipment under test for many directions can be measured by using this system. The uniformity of the field inside the space is estimated by numerical analysis, and then the effect for a radiated immunity test is characterized.