Measurements of screening effectiveness of cables assemblies over broad frequency range

The screening effectiveness against currents is expressed in terms of the transfer ZT and against charges (i.e. electric fields and voltages) in terms of the capacitive coupling impedance ZF (or associated parameters). For electrically long cables both effects act at the same time; therefore a separation of ZT and ZF is not necessary from the viewpoint of the user. Either equivalent transfer impedance or the screening attenuation may be an adequate measure (the typical criterion for an electrically long cable may be taken as L/20⩽1 whereby L=300/(f/MHz))