Application of Gaussian-ray basis functions for the rapid analysis of electromagnetic radiation from reflector antennas

A highly efficient Guassian beam (GB) method was recently developed to provide a relatively rapid analysis of large reflector antennas. This GB method is very efficient because it represents the feed radiation in terms of a set of very few rotationally symmetric GBs and provides an essentially closed form solution for the reflection and diffraction of each GB incidence on the reflector surface. In contrast, conventional approaches evaluate the radiated field via a numerical integration of the physical optics integral over the large reflector surface; such numerical techniques are time consuming for large reflectors. However, the fast GB method becomes less accurate if each GB illuminating spot on the reflecting surface is comparable to the overall reflector size, since its closed-form solution requires a small spot size. This limitation of the GB approach happens particularly in situations where the feed is located relatively far from the reflector, since the GBs are not able to remain narrow in the angular and spatial domains simultaneously, thereby creating too large a spot size on the reflector surface. The above limitation of the GBs is overcome here by introducing a Gaussian-ray basis function (GRBF), a hybridisation of a geometrical optics (GO) ray tube and a GB. Owing to its similarity with a GB in the amplitude variation transverse to the ray, its incorporation into any existing GB code is straightforward. Numerical results are presented to demonstrate the accuracy and robustness of the new GRBF approach.