Electromagnetic Penetration of a Composite Panel in a Perfectly Conducting Surface

The increasing use of advanced composite mate­ rials in, for example, aircraft skin fabrication raises concerns about the shielding effectiveness of electromagnetic enclosures made partly or completely of a composite material. Not only the reduced equiva­ lent conductivity of advanced composites in comparison to metals [ 1], but also the contact resistance along composite-to-composite and metal-to-composite joints, will contribute to a degradation in electromagnetic shielding by such enclosures. It is our purpose in this short paper to investigate one aspect of this problem, the low-frequency magnetic field penetration of a conductive (e.g., graphite-epoxy) composite panel in an otherwise perfectly conducting plane surface 'of infinite transverse extent and infinitesimal thick­ ness. We assume that the contact conductance between the panel and the surrounding perfect conductor is finite, so as to examine the effect of an imperfect electrical bond on the shielding afforded by the panel. We shall show, by formulating and then by approximately solving an appropriate boundary-value problem of potential theory, that the magnetic aperture polarizability of the composite panel, a m ,