A Fast Method to Compute Radiation Fields of Shaped Reflector Antennas by FFT

A rapid calculation method of the far-field radiation patterns of a shaped reflector antenna illuminated by a feed in an arbitrary location is reported. In this method، the equations of geometrical optics (GO) are used to calculate the reflected electric field using the radiation patterns of the feed and the parameters defining the reflector surface. These fields comprise the aperture field distribution which is integrated over the aperture plane by Fast Fourier Transform (FFT) algorithm based on low-size meshing of the aperture to yield the far-field radiation patterns and to calculate other antenna parameters. Shaped Reflector Antenna Design and Analysis Software (SRADAS) based on this numerical method can analyze and simulate all shaped reflector antennas with large dimensions in regard to the wavelength. SRADAS has been implemented and used in Information and Communication Technology Institute (ICTI) to analyze and simulate different practical parabolic and shaped reflector antennas. In order to confirm the integrity of the proposed calculation method، two practical antennas are analyzed using this software. The results are in good agreement with the results obtained by commercial software (Method of Moment) and measurement. Large shaped reflector antennas can be simulated by SRADAS fast and accurately.