A SIMPLE THEORY FOR OPTIMIZING FINITE-WIDTH ELF MAGNETIC-FIELD SHIELDS FOR MINIMUM DEPENDENCE ON SOURCE ORIENTATION

The effectiveness of single layer, finite width, planar extremely low frequency (ELF) magnetic held shields is strongly dependent upon the o rientation of the field sources, Since source information is difficult to obtain, the issue of designing shields which are independent of so urce orientation is important, sere, a simple analytic model for shiel ding by multiple layer, finite width, planar shields constructed from perfect electric and perfect magnetic material is presented, This is a ugmented by a study of conditions for which the perfect material appro ximation is valid, The simple model is used to determine strategies fo r designing shields which are independent of source orientation. It is found that two layer perfect electric/magnetic shields perform signif icantly beater than single layer shields.