Optimization Design Techniques For Antennas And Directional Couplers Based On The Differential Evolution Alorithms

As an important branch of engineering electromagnetics, optimization designtechniques have attracted much attention over years. The advantages of the differentialevolution (DE) algorithms, such as powerful search capability, easy-to-code, and lowspace complexity, make it very suitable for solving complex EM design problems.Therefore, the study of optimization design techniques based o n the DE algorithms is ofgreat theoretical significance and potential practical value. In this dissertation, based onthe DE algorithms, optimization design techniques for antennas and directional couplersare addressed. The main contributions of the dissertation are outlined as follows:1. Application of the classical DE algorithm to antenna optimization. Firstly, the DEalgorithm is applied to the optimization of the impedance characteristic of a widebandmicrostrip antenna. Then the design of a band-notched ultra-wideband antenna isachieved by the DE algorithm. The experimental results show that the DE algorithm isan effective technique for antenna optimization.2. Design of an ultra-wideband antenna using the Boolean DE algorithm. For thecompact UWB slot antenna, by optimizing its mesh-grid structure as well as the feedline structure, good impedance matching is obtained in the UWB band. Both thenumerical experiments and measured results demonstrate the effectiveness of the designmethod.3. Application of hybrid real-binary DE algorithm to antenna optimization. Ahybrid real-binary DE algorithm (RBDE) is developed for real-binary-mixed parameteroptimization problems in electromagnetics. A detailed implementation of the algorithmfor the design of an aperiodic array and an UWB antenna is presented. Experimentalresults show that the RBDE algorithm is a practical and effective optimizationtechnique.4. Pareto optimal design of ultra-wideband directional couplers usingmulti-objective DE algorithm. The design of broadside-coupled directional couplers isinvestigated by using the generalized DE (GDE) algorithm, and the optimal taperingshapes subject to each optimization objective are presented. Numeric results show thatthe GDE algorithm can provide the optimum trade-off between solutions in a3D Paretofront, which is an effective design technique for directional couplers.