MODELING OF EXTREMELY-LOW-FREQUENCY MAGNETIC-FIELD SOURCES USING MULTIPOLE TECHNIQUES

It is necessary to identify sources of magnetic fields in older to ana lyze shielding schemes. In general, it is difficult to specify actual sources. Here an alternative method to process magnetic field measurem ent data to create a simple model of a complex set of quasi-magnetosta tic sources is described. This method uses the maximum likelihood esti mation technique to calculate the coefficients of spherical and finite length cylindrical multipole sources whose positions have been define d by the user. If a good fit to measured data is achieved, the simple model can then be used to provide input data required by a shielding a nalysis program.