Research On The Key Technologies Of Antenna Near-field Measurement System

With the development of wireless communication technology and the continuous updating of communication equipment,antenna plays a vital role in the field of communication.People's strong demand for high-performance antenna promotes the rapid development of antenna measurement technology.Antenna far-field measurement technology first appeared,but due to the influence of measurement site and space environment,it is not suitable for some antenna measurement requirements.Therefore,people pay attention to the antenna near-field measurement technology.Antenna near-field measurement is to use the probe to collect data in the near area of the measured antenna,and obtain the far-field radiation characteristics of the measured antenna through near-field and far-field conversion.The near-field measurement has a series of advantages,such as high confidentiality,high measurement accuracy,all-weather operation and so on.The planar near-field measurement technology and spherical near-field measurement technology have become the focus of this field.The main contents of this paper are as follows:1.Based on the theory of spherical wave mode expansion,a spherical near-field phase recovery algorithm using double spherical iterative optimization is proposed,and the correctness of the proposed phase recovery algorithm is verified by simulation.2.Using network analyzer to improve the near-field measurement accuracy and frequency band expansion method.For the microwave vector network analyzer used in the antenna near-field measurement system in the microwave anechoic chamber,two methods are used to improve the measurement accuracy of the network analyzer,and the antenna measurement frequency band is expanded by combining the up and down conversion module and the RF amplifier,so that the frequency band of the antenna measurement system is expanded to the millimeter band,reaching 120GHz,and the test results are good.3.Using link budget to estimate the dynamic range of antenna measurement system in anechoic chamber,the near-field measurement accuracy can be improved.Based on the link budget,the dynamic range of the system is estimated to improve the system accuracy.Several different frequency band measurements are carried out in the antenna plane near-far field measurement system built in a microwave anechoic chamber to verify the accuracy of the measured antenna's 3dB beam width.The measured results show that the measured antenna's 3dB beam width accuracy is in less than ±5%.It is concluded that the measurement system has the features of high reliability and high measurement accuracy.