Asymptotic solution for the diffraction problem on a periodic array of microstrip radiators located above the surface of an infinite generalized cylinder, the curvature radius of which satisfies the condition of slow change along the guide, is considered. By using the matrix reflectivity coefficients, the problem is solved assuming the multilayer isotropic dielectric coating is present. For partial excitation the electric Green tensor function of Maxwell equations is written in closed form, which includes the Airy functions in the Fok definition and their first derivatives.