Near-field Imaging Analysis Of 2-dimensional Millimeter-wave Interferometric Radiometer

Interferometric synthetic aperture microwave radiometers are widely used in satellite remote sensing applications.In addition,near-field imaging is another important development area of interferometric synthetic aperture technology.On the one hand,the synthetic aperture radiometer system developed for space-borne applications often cannot achieve the required far-field conditions during the ground test phase,and the verification of the system imaging capability and some system-level indicators must be completed under near-field conditions.On the other hand,the practical applications of human body concealment of dangerous goods security imaging,close-range target imaging under harsh visual conditions,and detection of buried objects also impose urgent requirements on high-resolution passive microwave near-field imaging.However,the existing near-field imaging algorithms all have different degrees of defects,and the near-field imaging algorithms still need to be further explored.In addition,the two-dimensional antenna array is gradually widely used because of its advantages of instantaneous imaging,but the quantitative evaluation of the error of different two-dimensional antenna arrays under near-field conditions in domestic and foreign research is still less involved.In the above background,this paper builds a 2-D synthetic aperture near-field imaging simulation platform based on the Matlab,and implements functions such as target scene generation,near / far field forward simulation,near-field phase correction,and brightness temperature reconstruction.Then,based on the platform,the near-field imaging characteristics of the point source and the extended target are analyzed.The near-field errors of different two-dimensional antenna arrays under the same spatial resolution are quantitatively evaluated and compared.The effectiveness of the near-field phase correction algorithm is verified.In addition,the effects of different operating frequencies and antenna patterns on near-field imaging errors.In addition,a two-unit sub-millimeter wave near-field scanning interferometer based on a T-shaped scanning gantry was used to conduct near-field target imaging experiments.A Self-calibration near-field imaging method was proposed.This method uses the research of a near-field imaging simulation platform As a result,the receiver channel error and near-field phase error are corrected step by step.Compared with the near-field imaging method based on the reference point source,this method does not need to image the reference point source again,and has the advantages of simple operation and fast imaging speed.The main contributions of this thesis will be a reference for the conditions under near-field two-dimensional antenna selection and formation of near-field imaging test target,and promote the popularization of synthetic aperture radiometer in the near-field probe field.