Characterisation of cable feedthrough by measurements in nested reverberation chambers and comparison with simple theory

A simple theory for how the shielding effectiveness for a volume shield is affected when an isolated conductor is penetrating the shield is presented. The theory is based on basic circuit theory in combination with antenna theory and gives a good agreement with measurements using nested reverberation chambers for the considered frequency range 400 MHz to 4 GHz. The theory is used as an argument for a measurement method for the characterization of cable feedthroughs. Measurement results for validating the theory and for commercially available cable feedthroughs are presented.