Novel modular approach based on Gaussian beam diffraction for analysing quasi-optical multi-reflector antennas

A novel approach for analysing quasi-optical multi-reflector systems is presented. In the proposed method of analysis the input beam (from the feed or output from a previous reflector) is expanded into a set of elementary Gaussian beams. These are propagated to the reflector. Reflection is treated in a geometrical optics manner. Diffraction is treated by applying the canonical problem of a 3-D Gaussian beam incident upon an opaque Kirchhoff half-screen. Its asymptotic solution yields a so-called boundary-diffraction wave that complements the geometrical wave that corresponds to the reflected beam. The output beam is a superposition of all reflected and diffracted elementary beams and can again be expanded into a set of Gaussian beams, making the method modular and suitable for large multi-element quasi-optical systems