Thermal registration of electromagnetic fields by thin conducting films

The impedance approach was used to derive expressions for the coefficients of reflection, transmission, and absorption of a plane wave incident on a thin metallic film at arbitrary angle and polarization. Experimental results on the impedance approach (which is shown to be suitable for radio imaging) are obtained for wavelengths of 1-2 mm and for films made of Al, Ag, Au, Cu, and Ni. The thermal relief of the film which arises in the general case is shown to be determined by the tangential component of the perturbed electric field; however, depending on the impedance of the film, this relief can be close to the electric relief or the magnetic relief of the primary wave.