The effects of variations in wave impedance in the coupling of large lossy bodies to external electromagnetic fields

Describes a theoretical analysis of the illumination of a hollow, conductive object containing a wire by a non-planar wave. Much EMC testing is performed at antenna-test object separation distances that are small compared to the wavelength. The authors show that such 'near-field' (Fresnel zone) testing produces coupling responses markedly different from that encountered due to plane wave (where the wave impedance is 377 ohm) incidence. There is practical verification for this-in 1983, the effect was noted in an aircraft trial.<>