| In the practical world of reflector-antenna engineering, accurate analysis of a particular design is necessary to insure adequate performance before committing manufacturing resources. For some designs, traditional non-rigorous reflector antenna analysis tools, such as physical optics, may be inadequate. Due to the electrically large dimensions of typical reflector antennas, rigorous analysis can be very difficult if not impossible. The objective of this work is to develop a numerical tool for rigorously analyzing electrically large reflector antennas (50 or more wavelengths in diameter). In order to meet this objective, an efficient iterative EFIE (electric field integral equation) analysis method is developed that uses minimal computer time and memory resources.; Iterative solution techniques offer significant time savings over direct linear equation solvers. Typically, direct linear solvers (which are used in conjunction with the method of moments) require computer storage and computation times proportional to N3 and N 2, respectively where N is the number of unknowns. Iterative solvers can be formulated such that the computer storage and computation times are proportional to N2 and N, respectively. However, the EFIE has been traditionally difficult to solve iteratively due to convergence difficulties.; In this dissertation a stable iterative method for the EFIE is developed. In conjunction with this development, a new basis function is formulated that allows the iterative algorithm to be more efficiently used. The basis function near-zone fields can be partially computed in closed-form, substantially decreasing the associated computation time. In addition, the iterative algorithm is applicable to a simple parallel processing technique that allows the simultaneous use of several personal computers, connected over a standard LAN (Local Area Network) to analyze electrically large reflector-antennas. Using the proposed algorithm and the parallel processing technique, an offset reflector-antenna with a diameter of 50 wavelengths and approximately 100,000 unknowns is efficiently and rigorously analyzed using 10 networked personal computers. The analysis results are validated in some cases with experimental measurements of actual reflector-antennas. |
