Use of modified Gaussian beams to optimize shaped reflectors

An efficient electromagnetic method for the optimization of shaped reflectors is presented. The repeated computation of scattering from a reflector surface at each iteration, using the conventional numerical techniques of either physical optics (PO) or aperture integration (AI), usually makes the iterative procedures very inefficient for the synthesis of large reflectors. An asymptotic Gaussian beam (GB) technique has been developed and applied successfully to the fast analysis of reflector antennas of various shapes (Cabbage, H.-T. et al., Proc. IEEE Ant. and Propag. Society URSI Symp., vol. 4, p.2336-9, 1999). This GB technique completely avoids numerical integration and thus makes the analysis very efficient. Our method uses the GB technique, coupled with a local description of the primary source and the reflector. The primary source radiation is expanded using a modified Gaussian beams basis. An antenna pattern calculation is demonstrated on a reflector that is described by local parameters in a novel way. By virtue of these local properties and the use of a steep step descent algorithm, a basic display of antenna pattern optimization is presented to illustrate the effectiveness of our method.