Pattern Reconfirgurable Antenna Optimization And Design Based On Improved Genetic Algrorithm

As a new antenna technology, reconfigurable antenna has received extensive attention. The current distribution on the patch of the reconfigurable antenna is changed by controlling the switch states to change the characteristics parameters, without altering the basic structure of antennas. Because a reconfigurable antenna can fulfill the functions of multi-antenna, the antenna number can be greatly reduced and the purpose of light weight, small volume, low cost and good electromagnetic compatibility characteristics can be realized. Therefore, reconfigurable antenna will have broad application prospect.In current reconfigurable antenna research, the design of frequency reconfigurable antenna with uniform radiation partterns is more than that of pattern reconfigurable antenna with fixed operation frequencies. Though the design of pattern reconfigurable antenna is more difficulty, it can improve the performance of the system effectively. Reconfigurable antenna is required to reach the expected antenna performances in the various working states, that makes the antenna design is very complicated. Therefore, the optimization method combined with numerical simulation is used to design reconfigurable antenna in this paper.Firstly, genetic algorithm was improved to improve the global convergence rate and the convergence speed.an optimization program which is based on improved genetic algorithm and electromagnetic simulation software is developed.this simulation software is based on finite element method. The optimization program is used as tools designing pattern reconfigurable antenna. Using the optimization program, a reconfigurable antenna composed of small microstrip arrays and swich array is designed, the results show feasibility and validity of the optimization programe.A novel microstrip antenna with symmetrical folded dipole structure is improved to design pattern reconfiruable antenna in this paper, this antenna has the advantage of miniaturization and wideband. Two pattern reconfigurable antennas are designed though combining switches and adopting optimization program to optimize the antnna structure:1) omnidirectional and directional pattern reconfigurable microstrip antenna with the same frequency, in order to guarantee the operating frequencies of the two states are same,one tuning arm is added at the side of microstrip feed line. Simulation results show that the directional and omnidirectional radiation patterns are realized in the band of 3.76～4.3GHz.The impedance bandwidth is about 13% and the peak gain is 6.7dBi and 3.9dBi at 4GHz; 2) Beam scanning pattern reconfigurable microstrip antenna with the same Frequency, which has four swictable states corresponding four different radiation derections in xoy plane at 3.67～4.4 GHz, the impedance bandwidth is about 19%.