Study On Error Analysis And Diagnosis Method Of Spherical Near Field Measurement

Near-field measurement technology is the most important means of antenna measurement at recently.Spherical near-field measurement is a kind of near-field measurement technique.By collecting the near-field data around the virtual minimum sphere of the measured antenna,the complete antenna pattern can be obtained through the near-far field transformation program,which is the most effective method.Firstly,the synthetic plane wave propagation in different directions based on single sweep weighting is introduced,which can be used to obtain the far field information of the relevant test antenna in different directions.In near-field to far-field conversion based on feature-mode expansion,the near-far field transform algorithm can be evaluated by synthetic plane wave description and algorithm verification.The effect of the probe calibration and the effect on the measurement error can be easily investigated in a verification process based on the synthetic plane wave field calculation.Secondly,the influence of the spherical near-field measurement technique on the measurement error may be difficult to be directly evaluated,but it can be realized by applying computer simulation.By analyzing the effects of probe calibration and the truncation effect of the measurement range,the main beam and the first side-lobe in the far-field region are analyzed,and the actual measurement error is compared with the simulation error to draw the conclusion.Then,a near-field diagnosis method of array antenna based on equivalent electromagnetic flow model is given.The coupling equations between spherical near-field measurement data and the excitation of the array antenna are obtained by the relationship between the spherical near-field measurement data and the excitation of the array antenna,the cell pattern and the probe pattern.Finally,the standard horn antenna is used as the research model.Near-field data are obtained by using Insight simulation software,and the far field is obtained by the near-far field transformation program,and compared with the measured far field.A new method of near-field diagnosis based on far-field pattern is obtained through the comparison of the results,and the errors existing in near-field measurement are analyzed.