Optical and diffraction simulation techniques for large multibeam reflector

Geometrical optics (GO) based methods are widely used for modeling and parameters determination of big reflector antennas in the millimeter wave band, when the diffraction effects are small enough, and computations using methods that are more precise would take excessively long time. In this report, the result of GO modelling and optimization of the modified optical system of RATAN-600 radiotelescope which suggests modifications to the optical system.