Analysis And Design Of Anechoic Chamber

From more than half a century,with the rapid development of information technology,a variety of wireless terminals and the corresponding base stations have been built in all over the world,followed by the ubiquitous electromagnetic wave,which brings convenience to people,but also causes a serious electromagnetic interfere nce.The measuring equipment of electromagnetic wave is the necessary tool to analyze the radar cross section(RCS),estimate the antenna radiation performance and analyze the electromagnetic interference and compatibility.In addition to the military demand,it also needs a good test environment for the common industrial and academic research.Therefore,a crucial question is how to create a simple and correct electromagnetic testing environment.At first,the anechoic chamber is mainly used to solve the problem of antenna pattern measurement.Then because of its excellent performance,the anechoic chamber is widely used in scattering characteristics of radar,communication equipment and antenna radiation performance and electromagnetic measurement of automobiles,ships,aircraft and so on.The role of anechoic chamber is very important,but the cost of construction is equally expensive.In order to get a more intuitive understanding and planning about its performance before building an anechoic chamber,this paper gives a detailed introduction to the structure and function of the whole model of anechoic chamber,and the finite difference time domain method is used in the 400 MHz to 700 MHz band,while the geometrical optics method is used in the 700 MHz to 40 GHz band.The quiet zone performance of anechoic chamber is simulated and calculated,and the effect of different parameters(such as excitation source type and location,frequency,size of chamber and absorbing material etc.)is also researched.This paper focus on the finite difference time domain based on the anisotropic matching layer at low frequencies.A half-wave dipole and a simple log periodic antenna model are constructed with the algorithm as excitation source in anechoic chamber.O n the basis of the algorithm,the symmetry of the computational space is fully considered,and the memory optimization and the operation speed of the program are studied by the way of matrix partition.The results show that the optimized algorithm can run more than two times faster,and greatly reduce the computer memory requirements of the computer.In this paper,the far field expression of the standard horn antenna,the sizes of horn antennas and waveguide dimensions in different working frequencies are given.The method of further improving the performance of thequiet zone is discussed.At the same time,in order to facilitate the use of different professionals and intuitive ly express the simulation results,a simulation software of quiet zone performance of anechoic chamber is designed by the function of GUI in MATLAB software.According to the settings of the corresponding parameters,the software can quickly calculate the simulation results,and can also intuitively express the simulation results with two-dimensional maps,three-dimensional maps and lists form.Some operational data and graphics are export to facilitate the user to analyze and reference.The simulation results show that the simulated quiet zone performance is better in high frequency,which can meet the requirements of the quiet zone.The result still need to be improved in low frequency,because of the limitations of computer memory and the simulation of the excitation source is relatively simple,resulting in a certain error in the excitation source compared with the actual radiation field,which is the part can be improved in the future.