Ferromagnetic Shielding Related to the Physical Properties of Iron

The reasons why a nonlinear mathematical treatment of the shielding effectiveness of iron is required are discussed. A brief traveling wave solution is given to the EMP shielding problem when iron material is used. It is estimated that a one mil thick HIPERNOM sheet can provide shielding against a 104 volts/meter EMP of 13 microseconds duration. It is shown that iron shields more effectively than copper. The shielding efficiency of several commercial grades of iron is measured in the frequency range of 30 Hertz to 57 Kilohertz. Various physical factors influencing shielding effectiveness in this frequency range are discussed.