Application Of Plane-wave Synthesis Theory Based On Genetic Algorithm

By means of the method of combining theoretical analysis with computer simulation and experiments test , the technique of plane-wave synthesis based on genetic algorithm is studied and applied into near-field antenna measurements . The main research work in this thesis are as follows:Firstly, the basic theory of plane-wave synthesis is introduced briefly. The theory of the genetic algorithm is introduced in detail, and for the application in this thesis the basic common multi-objective optimization methods are introduced. Combined with the practical work in this thesis the detailed process of the genetic algorithm utilized in this thesis is given. Genetic algorithm is applied into the technique of plane-wave synthesis and the technique of plane-wave synthesis based on the least square method is also introduced briefly.Secondly, on the basis of theoretical analysis , the two-dimensional and three-dimensional calculation model are established. The application of the real coded genetic algorithm in the problems of two dimensional and three dimensional plane-wave synthesis is company simulated and the cases with beam scanning and without beam scanning in the two kinds of problems are studied respectively. At the same time, the results obtained by the genetic algorithm are compared with the results obtained by Least Square method and the theoretical results. The comparison of the results proves the correctness and validity of the method presented in this thesis as it is applied in the problems of plane-wave synthesis. The results of computer simulation show that under the condition that the size of the scanning plane and the region under test remains unvaried,the quasi-plane wave with higher quality can be synthesized by genetic algorithm .Finally, with the open-ended rectangular wave guide as the probe in plane near field antenna measurements instead of the theoretical probe in three-dimensional calculation model, the method of plane wave synthesis presented in this thesis is computer simulated and the results of computer simulation prove the correctness and validity. In order to further validate this method, the horn antenna is tested and the experimental results obtained by the method present in this thesis are computed with the results obtained by least square method and traditional method.The results of comparison show that in the case that the scanning plane and the area under test remain unchanged , the proposed method in this thesis has better precision as the size of the scanning plane is relatively small and the samling internal is relatively large ,which proves the validity and advantage of the technique of plane wave synthesis based on genetic algorithm for improving the measurement precision and efficiency as it is applied into near-field antenna measurements.