Magnetic shielding of a cylindrical shield in nonlinear material with hysteresis

Fast analytical expressions are presented to find the shielding effectiveness of cylindrical shields in ferromagnetic nonlinear materials with hysteresis. The magnetic material is characterized by a complex permeability defined by the Preisach formalism. The approach to calculate the shielding factor is based on the transmission line method (TLM). The shield is considered as a transmission line that partly reflects, partly absorbs and partly transmits an incident wave. As the considered shield consists of hysteretic, non-linear material, the shield is divided into a number of linear sublayers, each having a space independent permeability. In other words, the nonlinear shield is replaced by a set of linear shields and the permeability that is continuously varying in the nonlinear shield is replaced by a piecewise constant complex function.The permeability is function of the magnetic field H to model the nonlinearity.