An Experimental Study of the Effects of Internal Loading on the Measured Shielding Effectiveness of Printed Circuit Board Shields

The measurement of shielding effectiveness of printed circuit board shields can be undertaken with the shields connected to a measurement jig installed in a reverberation chamber. The internal loading of the printed circuit board shield is not normally accounted for in Shielding Effectiveness measurements. The measurement jig used in this paper has internal loading in the form of a stripline that is used to measure the energy coupled into the shield. Normally this stripline is terminated in matched loads. In this paper we illustrate the effects on the measured Shielding Effectiveness of the printed circuit board shield of changing the terminations of the internal stripline and of the addition of extra absorbing material into the shield.