Gaussian Beam Tracing Method For Substrate-lens In Quasi-optics System

Quasi-optical technique is a challenging field intermediating of microwave technology and optical technology. Nowadays quasi-optical systems have been widely employed in the fields of space exploration,radio astronomy, meteorological satellite and imaging. This project mainly concerns about Gaussian-beam (GB) tracing method for the prediction of GB propagation through dielectric lens.At first, this thesis introduces the Gaussian-beam propagation,transformation of Gaussian-beam, which is the fundamental theory of quasi-optical technique. Then, two important methods of electromagnetic computation in quasi-optical system are introduced. Taking accuracy and computational time into account, the thesis mainly introduces the Gaussian-beam refraction method of general astigmatic Gaussian beams,with detailed derivation of the method. To verify the accuracy of this method, simulation models are established and the results are in good agreement with the measured ones.The refraction of arbitrary beams shooting to arbitrary surface can be analyzed by using this method. The field distribution can be obtained from any incident field using point matching technique, being suitable for arbitrary cascaded quasi-optical components. Moreover, the design and experiment of lens dose not lose generality, to verify the accuracy of the algorithm. At last, this method of Gaussian-beam tracing can be used to calculate the far-field pattern of the antenna.This algorithm based on Gauss-beam has the advantages of good accuracy and short computation time, which can be used in the design of quasi-optics systems with more complex structure.The main outputs of this project are as follows: (1) a model has been set up for the description of the Gaussian beam propagation in dielectric lens; (2) Implementation of the algorithm; (3) An experimental system has been built so as to verify the algorithm.