| Being an approximate HF method in evaluating EM scattering, the complex ray method (CRM) is valuable in actual applications, mainly benefited from its simple physical model, convenient mathematical formulation and computational efficiency, especially with the scenes of scattering from complex objects. Typical procedure of EM scattering evaluation application with the CRM can be concluded as the following steps:· Discretization of incident plane wave, replacing the incident wave with a bundle of complex rays (complex source points) in parallel directions, which is named as complex ray expansion (CRE);· Evaluating the contributions at a given observer point from each complex rays, with the use of ray tracking, complex ray paraxial approximation and field intensity calculation;· Repeat the former calculation and sum all the contributions from the rays to present the scattering pattern of the specific target.Several kinds of typical targets can be specified for its scattering characteristic with the method mentioned above, where the theoretical results are in good agreement to the experimental ones, which suggests that the CRM can be further applied to the analysis of the scattering from complex/combinatory targets.It is obvious that in the extended application there is no ready-made experimental scattering patterns to be referred, it is of great importance to develop a systematic research on the computational accuracy and error control techniques of the theoretical method. Also, a better understanding on the computational accuracy and error control techniques of the CRM will make it to become a generalized procedure usable in developing a standard scattering evaluation software for more kinds of targets.A few literatures have been roughly related the researches on the accuracy of the scattering evaluation results of the method. As an enlightening one, Du and Ruan have proposed to define a total error measurement (TEM) of the complex ray fields referring to the definition of Norm in L2 space (Journal of Electronics, 16 (4): 428-431, 1994). With a straightforward derivation in spectra domain and the TEM they developed, it is concluded that the error of scattering field is determined by spectral transformation function of scattering objects and the injected total error ofIVthe incident wave when simulated by a bundle of complex rays. However, this error measurementis characterized by its definition, as similar to that of the root-mean-square error. It can not be used to give a description of the dispersive details of the complex rays or the scattering expressed in complex rays. Nor can it be used to specify the complex ray expansion parameters (the beamwidth of the complex ray, and the distances between the neighboring complex source points) which are needed to make the calculation results accuracy enough.With this recognition on the accuracy researches of the CRM, this dissertation tries to make a systematic analysis on this topic. The following works have been completed.First of all, an analysis model is introduced, in which a generalized large aperture cavity target is reconstructed into simple targets like plates and cylinders, and the CRM together with some other ray methods like, collective rays, diffracted ray etc is used to calculating the scattering. It is prospected that the model can be used as a common solution to those kind of scattering scenes. Some ray techniques such as CRE, complex ray tracing (CRT), complex ray paraxial approximation (CRPA) are discussed in detail, among which CRE and CRPA are regarded as dominantly accountable to the error of the calculated scattering pattern.In fact, with the TEM method, several topics are analyzed including the error characteristics of complex ray field as HF zero-order asymptotic solution of wave equation, and those of complex ray expansion and scattered field calculation in the dissertation. It is concluded directly that, the complex ray field can provide a uniformed formulation to the radiation from Gaussian distribut...
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