Research On Near Field Measurement And Probe Compensation Technology

With the ever-changing antenna technology,it is urgent for the demand of antenna measurement technologies.There are so many measurement methods,such as the far field measurement,the compact range measurement,and the near field measurement.The near field measurement has been widely applied recently,because it can obtain the 3D pattern of the antenna under test(AUT),needs relatively small a workplace,and be limited with less condition.In the near field measurement,a small probe,whose radiation properties are known,is applied to measure the near fields of the AUT on a sampling surface containing almost all energy,and then the near fields are transformed to get the far field of the AUT,which is termed as a near field to far field transform algorithm(NF-FF).The near field measurement can be divided into three categories in terms of the scanning surfaces: the planar near field measurement,the cylindrical near field measurement,and the spherical near field measurement,etc.Except for the mechanical position errors of the scanning probe,the NF-FF will decide the accuracy of the measurement.So the purpose of this thesis is developing a planar NF-FF algorithm and a spherical NF-FF algorithm.The main work of this thesis is as follows:1.Study the principles of planar near-field measurement and accomplish a planar NF-FF algorithm without probe compensation.And we propose a new GAUSS-FFT method to evaluate the integrals much more efficiently.Numerical experiments show that the proposed algorithm is more accurate than the traditional NF-FF transform based on conventional FFT,especially for the ultralow side-lobe antennas.2.Study the probe compensation method based on the Lorentz reciprocity theorem,and accomplishes a planar NF-FF algorithm with probe compensation.We propose to use the higher order moment method to efficiently obtain the 3D pattern of the waveguide probe,which is applied to determine the plane wave spectrum of the AUT.Measurements show that the proposed method is in good agreement with the commercial software.3.Study the principles of spherical near-field measurement and accomplish a spherical NF-FF algorithm without probe compensation.Two simulation antennas and an actual antenna validate the accuracy and stability of the proposed algorithm.4.Study the probe compensation method based on the spherical wave transmission formula,and accomplishes a spherical NF-FF algorithm with low-order probe compensation.Numerical experiments show that the results of the proposed method are in good agreement with the results of the higher order moment method.