Comparison of test methods for the characterization of shielding of board-to-backplane and board-to-cable connectors

Abstract

We present the work carried out in the SOBITS project executed within the framework of the European Measurement and Testing program. The goal of the project was to compare different methods for characterization of the shielding performance of board-to-backplane and backplane-to-cable connectors used in telecommunication and computer systems. Four measurement methods have been selected. Dedicated test samples have been designed and developed in order to enable the measurement of the shielding characteristics of the connectors under test with all methods. Different shielding configurations were considered, in order to determine the influence of the quality of the shield. Single-ended as well as differential excitations have been considered. Among the test samples, a nonshielded version was designed for each signal/ground configurations. This sample was used as a reference. The definition of the quantities that describe the shielding performance is different for each of the measurement methods. Conversion formulas between these quantities have been formulated. They were verified by measuring a reference device that is easy to measure by all methods. Thus we were able to compare the relative shielding effectiveness of the various shielded board-to-backplane and backplane-to-cable connectors for all four measurement methods. The relative shielding effectiveness of a shielded connector was calculated with respect to the nonshielded version. We also compared the different shielding performance results obtained with each measurement method individually.