Study On The Shape Technology Of Double-reflector Antennas

The double-reflector antennas represented by Cassegrain antenna and Gregorian antenna are widely used in the satellite communications. The design of the double-reflector antenna with low sidelobe is taken as the emphasis. After a brief introduction to the construction and design of normal double-reflector antenna, with Gregorian antenna being the target, the paper studies shape and analysis technology for double-reflector antennas based on Geometric Optics (GO).In the study of shape technology, the relationship between the aperture fields and the far fields are analyzed firstly, the control of the far field sidelobe is realized by ajusting the aperture fields distribution by Taylor method, followed by its validation through computation. Then, based on the GO and differential geometric theories, after the study of the shape process of the main and sub-reflectors for the double reflector antenna, its computing formulae and arithmetic flow are given. When analyzing the characteristics of the antenna, the paper makes a detailed study of the ray trace and aperture integration technologies, and deduces the formular of the integration for the far field radiation of the field on a triangular region based on the value inset and parameter transmition, thus simplifying and speeding the calculation of the far field. And its computing formulae and arithmetic flow are given.Based on the arithmetic flows above, the shape and analysis program for Gregorian reflector antenna are developed, and by using this program, a shaped Gregorian antenna meeting spetial parameters demand is designed, thus verifying the validity and practicality of the arithmetic and program.