Influence of coupling of dielectric waveguide and reflective grating on radiation characteristics

Influence of the gap between the planar dielectric waveguide and the reflective grating on the radiation characteristics of the antenna of diffraction radiation has been investigated on the bases of the accurate two-dimensional model. It has been shown that decreasing of the gap does not necessarily result in increasing of the efficiency of conversion of the surface waves into spatial ones. Drastic change of the radiation characteristics in the saturation mode has been revealed.