Research And Development Of Diffracted Gaussian Beam Analysis

Millimeter-wave and terahertz band,intermediating of microwave and the infrared,is a band of great significance and a relatively new area in the electromagnetic spectrum study.And millimeter and sub-millimeter wave systems are gradually used to the field of radiometer,navigation,space equipment,radio astronomy,and application for military field.Quasi-optical technology is an important means to analyzes and design millimeter-wave and submillimeter transmission.And Quasi-optical devices bear the advantages of being relatively easy to manufacture,high power capacity,operating in multi-band multi-polarization,less path loss.Therefore,it is widely used in millimeter-wave and submillimeter transmission analysis and design.Up to now,.one popular commercial software most commonly used in the analysis and design of quasi-optical system is GRASP.It is based on physical optics and some other auxiliary numerical analysis methods.As PO' calculates with.a large amount of current integration,a drawback is that the analysis is very time-consuming when electrically large reflector is analyzed.On the other hand,GO(Geometrical Optics)is suitable for design phase due to its computational accuracy.Initially,DGBA is based on geometrical optics and diffraction method,developed by Queen Mary,University of London,takes the advantage of the high computing efficiency of geometric optics,and accuracy of diffraction.But the previous version of DGBA is only capable of two-dimensional symmetrical structured modeling,which is a major limit in contrast with the commercial software GRASP.For example,the three-dimensional structure is often employed to be more compact.This thesis proposes a new modeling method to extend DGBA to be capable of analyzing three-dimensional asymmetric structures.Then,the reflection of Gaussian beam is discussed in detail.The last part of this thesis is devoted to the parametric analysis.It is revealed that DGBA method is dependent on the parameters of the sampling period,too big or too small value of which often leads to inaccurate results.