Scattering from thin dielectric disks

A solution for scattering from thin dielectric disks has been obtained by approximating the currents induced inside the disk with the currents which would exist inside a dielectric slab of the same thickness, orientation and dielectric properties. This procedure yields an electrostatic approximation when the disk thicknessTis small compared to the wavelength of the incident radiation and yields a conventional physical optics approximation when the dimensionA, characteristic of the geometrical cross section of the disk, is large compared to wavelength. When the ratioA/Tis sufficiently large one or the other of these approximations applies, regardless of the frequency of the incident radiation. Consequently, the solution provides a conventional approximation for the scattered fields at allkA. As a check on this conclusion, a comparison has been made between measurements of the radar cross section of thin dielectric disks and the cross sections predicted using this theory. Agreement was found for thin disks with both large and small values ofkA.