Shield behaviour of communications cables

The screening effectiveness of communication cables is vital information for EMC and crosstalk related issues associated with the selection of system cabling. Surface transfer impedance measurements are suitable in the lower frequency range and reverberation chamber measurements are suitable to determine behaviour at higher frequencies. This paper, primarily addresses the issue of conversion at, and accuracy of, the interface between these two regions, demonstrating that close agreement between the contiguous regions is obtainable. Secondly, a transmission line matrix (TLM) approach to predicting the performance of a braided coaxial shield, which simulates the overall system, including longitudinal effects, is presented. The TLM model and experimental studies are compared, demonstrating a high mutual confidence in the experimental approaches and the numerical prediction.