Limitations in the Measurement of the Shielding Effectiveness of Aeronautical Multi-ply CFC Laminates

Modern aircraft employ profusely carbon fiber composites (CFC) for their construction. Then, it is mandatory to characterize the behaviour of this kind of materials for its use under harsh electromagnetic environments. In that sense, this paper presents the application of two standards, the ASTM D4935 and the IEC 61000-4-21, to the measurement of the shielding effectiveness (SE) of aeronautical multi-ply CFC laminates frequently used for the construction of aircraft. Each technique is well suited for a specific material or realization and a specific frequency range. So, both techniques are complementary and should be developed in parallel. Taking into account the high SE expected for this kind materials, the set-ups imply the measurement of very low signals, that poses an experimental challenge that has to be faced. Then, in this study, different test samples and realizations of CFC materials have been fabricated and measured. Improvements on the traditional measurement procedures have been applied, obtaining promising results.

I. Introduction

At the present time, modern aircraft operate under very aggressive electromagnetic conditions, which makes them an easy target for electromagnetic interference (EMI) [1]. This obliges the aircraft manufacturers to consider such EMI effects both in the design phase and in the avionics certification, since it is necessary to guarantee that the electronics within the aircraft are not affected by such effects.