Assessment of shielding effectiveness and percolation threshold of composite materials

Abstract

This paper deals with the protection of avionics of small airplanes in an electromagnetic environment. Various composite materials are used for this purpose. The mechanical properties of these materials are very well described. On the other hand, the electrical properties are described insufficiently. A fabric with long copper-plated polyamide fibers was selected as a suitable shielding material. The aim is to verify the shielding effectiveness of the fabric by measuring the transverse electromagnetic wave on the coaxial line. Further, determine the flat fiber concentration required to achieve a certain shielding efficiency of given composite sample and its percolation threshold which is an important parameter determining the conductivity of the composite material. It is therefore possible to determine the critical content of the filler in which the composite material starts to act as a conductor.