Antenna Optimization And Design Based On Differential Evolution Strategy

An optimization program which is based on differential evolution strategy and electromagnetic simulation software is developed. The simulation software is based on finite integral method. Three kinds of antennas are designed through the optimization program. They are electromagnetically coupled broadband microstrip antenna, circularly polarized short helical antenna and high power double ridged horn antenna.First, the code of differential evolution strategy is written by analyzing its principle and characteristic. The code's correctness is validated with several canonical test functions. The paper develops the optimization program that can be applicable to optimization design of antennas and microwave passive components. The operation platform of the optimization program is the macro language interface provided by the electromagnetic simulation software. The simulation software has the powerful function of setting up solid models and plotting out computation mesh automatically. The theory base of the optimization program is differential evolution strategy. Using the optimization program, a coax waveguide transition component is designed, which proves feasibility and validity of the optimization program.The paper designs electromagnetically coupled broadband microstrip antenna, short helical antennas with good axial ratio performance and broadband high power double ridged horn antenna. Work frequency band of the designed broadband microstrip antenna is between 3.74GHz and 4.48GHz. Its voltage standing wave ratio is less than 2.0 at this frequency band, and its impedance bandwidth is about 18.0%. Axial ratio optimizations for two kinds of short helical antennas are carried out. One is short cylindrical helical antenna. Its axial ratio in the direction of helical axial is less than 3dB, and the radiation in the direction of helical axial is realized at the frequency band 3.6GHz～4.9GHz. Its axial ratio bandwidth reaches 30.5% for the 3dB axial ratio criterion. The other is short tapered helical antenna. It also has a radiation in the direction of helical axial, and realizes a less axial ratio than 3dB at the frequency band 3.7GHz～4.4GHz along helical axial. Its axial ratio bandwidth is about 17.5%. The work frequency band of the designed broadband high power double ridged horn antenna is between 0.37GHz and 0.42GHz. Its impedance bandwidth is about 12.6%, and realizes antenna gain about 7.5dB at above frequency band.At last, the radiated field of axial-mode helical antenna and double ridged horn antenna is analyzed at this paper. Several different time domain waves with different ascending time and degressive time are fed into axial-mode helical antennas, and different radiated fields are gained. At the same time, the damped sine time domain waves with different attenuation speed are fed into the double ridged horn antenna, and different radiated fields are analyzed.