The Study On Near Field Measurement Software Of Antenna Based On CGFFT And Method Of Equivalent Magnetic Current

With the rapid development of modern science and technology,antenna measurement techniques,including far-field and near-field measurement techniques,in the modern antenna technology and military research in the field of increasingly important position.Antenna as an indispensable part of wireless communication equipment,the quality of the direct impact on the quality of the entire system performance is good or bad.As the most direct method to test the quality of antenna,antenna measurement is more and more valued by people.Near-field measurement technology is an important means of testing the antenna,the near-field measurement is not affected by the environment,weather conditions,thereby increasing the accuracy and scope of measurement.In this paper,the theory and numerical simulation of the antenna near-field measurement method based on the equivalent magnetic current method is firstly studied to provide theoretical and experimental basis for near-field antenna measurement.Secondly,a set of near-field measurement software system is developed based on the theory.Provide theoretical and engineering application reserves for building a complete planar near-field measurement system.The main work and research results of this paper are as follows:(1)The near-and-far field transformation principle and algorithm of antenna near-field measurement are studied.This algorithm is based on the equivalent magnetic current method to realize near-and far-field transform of aperture antenna,and is solved by conjugate gradient fast Fourier transform(CGFFT)algorithm.The equivalent magnetic current of the aperture surface of the antenna is calculated according to the principle of equivalents and the principle of mirror image.Moment method is introduced to convert the integral formula Green formula into a matrix equation.By reasonably selecting the scanning sampling coordinates,the matrix equations can be constructed into a circular Toeplitz block matrix.The CGFFT algorithm is used to obtain the equivalent magnetic current of the antenna aperture surface,and then the far field radiation pattern of the antenna can be accurately calculated.Using Matlab software and Hobbies software numerical simulation,the far-field and far-field transformations of the paraboloidal reflector antenna were studied.The far-field pattern results show that the method can accurately invert the far-field radiation characteristics of the antenna in the range of 120.(2)Developing a set of antenna plane near field measurement software system.The software implements a user input interface,communication functions with the near-field scanner lower position machine,near-field data acquisition,image and result parameter display interfaces and processing functions,scanning motion coordinate tracking,near-far field conversion algorithm processing,and measurement result database management.Printing and other functions.The software controls the scanning frame probe to scan the near field of the antenna,and receives the near field electric field strength measured by the network analyzer.The near-far field algorithm dynamic link library of Matlab is used to invert the far field antenna pattern of the antenna,and the result is displayed in the graphical interface.Can realize coordinate transformation,normalization,data smoothing and other post-processing functions.(3)In order to save the collected data or the processed data,the database is used to save the data in software development in this paper,which can improve the storage efficiency of data storage.The tables in the database mainly include:amplitude/phase value tables,parameter display tables,and far field electric field value tables.