The prediction and control of low frequency magnetic field emissions

Electromagnetic field emissions from everyday objects are coming under closer scrutiny at the present time for various reasons. The paper describes an attempt to find a method for estimating the AC magnetic moment for simple machines (power transformers, induction motors). This is a measure of their H-field emission which is independent of separation distance. A method for determining magnetic field reflection loss is described. This is no better than the accepted method of Schelkunoff (1934), but may enable those who think in terms of circuit elements to grasp the principles involved. The reciprocity theorem is used extensively, as interchanging the source and receptor can simplify calculations by enabling simpler mathematical expressions to be used