A measurement setup for the detection of shield inhomogeneities of built-in multiconductor cables based on a differential sniffer method

In modern aircraft, often shielded multiconductor cables are used in order to realize a secure data transmission between electrical devices. During long life operation, these cables sustain damages from different sources. Arcing, corrosion and mechanical deformation, respectively, feature severe conditions for aircraft often leading to relatively small damage on the cable insulation and the shield. Considering EMI aspects, an inhomogeneity on the shield can endanger the data transmission due to increased coupling of external disturbing electromagnetic fields. In this paper a measurement setup is presented-based on the differential sniffer method-allowing localization shield inhomogeneities of small size on already built-in cables. For this purpose four equally constructed H-field sensors with field detection units are arranged in parallel in order to measure the radiated field around a cable shield. Measurements at damaged and intact parts of the cable are performed over a broad frequency range and compared with mathematical approximations.