Radiation of a ring current above a semitransparent disk

Asymptotic formulas for scattering patterns of the fields produced by the magnetic ring currents are obtained. The ring current has harmonic azimuthal dependence with single variation and locates coaxially above a semitransparent disk. The Kirchhoff approximation and the stationary phase method are used. The asymptotic formulas for scattering patterns are used for optimization of the disk transparency to reduce the back radiation of the ring magnetic current. The results of optimization were verified using the numerical solution of the singular integral equation for the optimum transparency.