Efficient analysis of large cylindrical reflector antennas using a nonlinear solution of the electric field integral equation

Abstract

The need to design large reflector antennas for optimum gain, radiation patterns, cross polarization and noise temperature continually drives the need for more exact analysis techniques for these types of antennas. An alternative method of solving the electrical field integral equation, applicable to large reflector antennas, is presented. This method requires far less subdomains per wavelength than the method of moments technique. In this analysis technique, the amplitude and phase (as opposed to the real and imaginary parts) of the surface current density are discretised into linear subdomain basis functions. By matching the boundary conditions on the surface of the reflector, a system of nonlinear equations is constructed and solved using iterative techniques. This basis function is far more suitable for large reflector antennas since the amplitude and phase of the surface currents vary quasi-linearly (whereas the real and imaginary parts of the current are highly oscillatory). This technique was inspired by the Ludwig (1968) algorithm for evaluating radiation integrals. The nonlinear technique is used to obtain the solution of the two-dimensional TM/sup z/ (magnetic field orthogonal to the z-axis) electric field integral equation, and is subsequently used to solve the radiated fields of cylindrical reflector antennas. Although this development was done for the two dimensional case, the technique can and is currently being developed for the three dimensional case. >