Scaling Laws for Large Shields in Quasi-Stationary Magnetic Fields

Abstract

The application of the classical scaling laws of electro-magnetic fields to the design of a scaled-down model of, say, a building-sized shield is often difficult, even when using the simplifications permissible with a quasi-stationary magnetic field. The reasons are that (i) the scaled wall thickness often becomes impractically thin and (ii) the required scaling of frequency sometimes reduces the ratio of intrinsic wave-length in air to the enclosure length such that the quasi-stationary field theory no longer applies. In the case of a completely closed shield these limitations can be circumvented by having a model with two distinct geometric scaling factors, one for the wall thickness and one for the overall dimensions. The modified scaling laws governing this type of model are derived.