Research On Correlative Technology Of Spherical Near Field Fast Measurement

Near-field antenna measurement is an important test method in the field of antenna measurement.Near-field measurement has gradually become the main test method due to its unique advantages such as high security and strong anti-interference ability,especially the spherical near-field test technology based on spherical scanning develop rapidly.The acquisition of near-field data,the realization of near-far field transformation algorithm,probe compensation and error analysis are the four main research aspects of spherical nearfield measurement.In spherical near-field measurement,the problem of long test time and low efficiency due to too many sampling points has always been the shortcoming of spherical near-field measurement.This paper mainly studies the design and compensation theory of spherical helical scanning and broadband dual-polarization probe to improve the measurement efficiency of spherical near-field.Firstly,based on the non-redundant representation of the electromagnetic field,the sampling criterion of the spherical helical scanning is determined,the spherical helical equation is established,the spherical helical scanning model is determined,and the reconstruction algorithm for recovering the near-field data is established.Then,using the horn antenna as the simulation model,the traditional scanning method and the spherical helical scanning method are used for numerical simulation transformation.Spherical helical scanning is achieved within acceptable error limits.Finally,it is found that the spherical helical scanning method adopted in this paper can improve the sampling efficiency compared with the traditional spherical scanning,and the error can be controlled within an acceptable range,thus verifying the feasibility of the method.Secondly,a dual-polarization probe based on the traditional Vivaldi antenna implementation is designed.A single-polarized probe antenna with a working frequency band of 0.6GHz6GHz is designed through miniaturization techniques such as resistance loading and slot line loading.The size is 90mm × 150mm × 1mm(0.18λL×0.3λL×1mm),and λL is the wavelength at 0.6GHz.The radiation pattern of the frequency point has good flatness and symmetry.The two antennas are then placed crosswise to form a dual polarized probe.Finally,the probe compensation algorithm is introduced into the spherical near-far field transformation,and the compensation algorithm suitable for the dual-polarized probe is explored based on the low-order probe.In terms of experimental verification,the near-field data of a group of horn antennas are measured in an anechoic chamber,and the far-field pattern of the horn is obtained through the near-far field transformation with probe compensation.Finally,the effectiveness of spherical helical scanning method and dualpolarization probe compensation to improve the speed of spherical near-field measurement is verified.