Analysis of beam waveguides for reflector antenna systems

The purpose of the present paper is to describe computational methods for the analysis of a realistic beam waveguide (BWG) at X-band, using physical optics (PO) and the geometrical theory of diffraction (GTD). The results presented illustrate that both PO and GTD are very useful tools for the analysis of even large and complicated reflector antenna systems. The agreement between the methods provides a good check of the validity of the results. Further, GTD gives the user an insight in the actual diffraction processes that are taking place, a feature which is very helpful during the design of the antenna system. The applicability of GTD has been demonstrated at X-band. Since GTD is a high frequency approximation it will be even more valid at Ka-band. This is an important conclusion because the computer time for PO increases with the frequency raised to the power of four and a PO calculation at Ka-band is therefore not practically feasible.