Determining Cable Shield Behaviour

摘要

As technology advances, the role of electromagnetic compatibility becomes more dominant in the design of distributed electronic systems. In high performance applications the leakage of energy into and out of cables is an important source of interference. It is widely acknowledged that cables are often the 'weakest link' of any large electronic system. This paper examines theoretically the surface transfer impedance of braid-shielded cables and compares these results with those obtained practically. Expressions for the transfer impedance are presented as improved tools for the analysis of tape-shielded cables. The paper then goes on to investigate the shielding effectiveness of a cable with a braided shield using a mode stirred reverberation chamber, then, by using a transfer function, converts the surface transfer impedance results into shielding effectiveness and compares these results with those obtained previously. Whilst this is applicable to other types of cable, this paper concentrates on coaxial systems.