| Summary: | 碩士 === 國立暨南國際大學 === 電機工程學系 === 99 === The main purpose of this thesis is to study and optimize antennas using genetic algorithm in conjunction with the IE3D and HFSS simulators. Many parameters affect the antenna performance in the design of an antenna. Traditionally, an antenna is designed using a trial-and-error approach based on the designer's electromagnetic experience. However, it is very time-consuming to tune the parameters of the antenna structure repeatedly to get a good result. The better solution of an electromagnetic problem can be obtained using genetic algorithm. Proposed automatic scheme in this thesis can improve efficiency and quality of the design works, decrease cost of materials, and increase the accuracy of the simulated results. In this thesis, the applications discussed include three topics. Firstly, we use genetic algorithm, which verified by test functions successfully, to optimize the array factor of a uniform linear and a non-uniform circular array antenna. The optimization objectives include the lower side lobe level, desired beam pattern, and first null bandwidth. Secondly, we use the designed genetic algorithm combined with the electromagnetic simulation software to optimize the logo-type antenna to achieve the reflection coefficient and impedance bandwidth. Result shows that the initial antenna performance is quite poor; however; the optimized result is much better than the initial one. Thirdly, we use the proposed method to optimize the tree-fractal antenna with the angle of the structure parameter and its directivity. Simulated and measured results of the tree-fractal antenna agree with each other very well. Obtained results show that the different complex electromagnetic problems can be solved successfully by the proposed optimization method. Finally, we use MATLAB to design the graphic user interface for the proposed method. Users can easily input the parameters and ranges of the antenna structure which is to be optimized in the optimization process. Therefore, users do not need to deal with the modification of the code. Such automatic and convenient scheme is a trend in the future. Hopefully these research works can provide great helps to electromagnetic community.
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