Electromagnetic Relationships Between Shielding Effectiveness and Transfer Impedance

There has recently been a proliferation of measurements of the magnetic and electric shielding effectiveness of composite materials. In order to relate these measurements, the transfer impedance concept can be used. Approximations relating surface transfer impedance to shielding effectiveness are derived for basic shield geometries. The independence of surface transfer impedance from geometry and incident field type is then exploited so that shielding effectiveness data for basic shield geometries may be extended to calculate the electromagnetic shielding for more general geometries.