Analysis Of Millimeter Wave Radiation Characteristics And Imaging Characteristics Of Metal Targets

With the development of information technology,the detection and recognition of metal targets has always been an important research direction in both military and civil fields.Passive millimeter wave can distinguish metal targets in harsh environment such as smoke,fog,dust and so on because of its unique band advantage.Even better,passive work contributes to excellent concealed performance.At present,millimeter-wave has been widely used in precision ammunition guidance and ground armored target detection and anti-detection.In general,the metal targets in reality have complex three-dimensional structures,which lead to more complex radiation reflection paths than those plane targets,and correspondingly,its millimeter-wave radiation images has more aliased edges witch characteristics cannot be easily extracted.In this paper,the above-mentioned characteristics of the stereoscopic metal target are studied,the main research work is as follows:(1)The basic principle of millimeter wave radiation,millimeter wave radiometer system and radiometer calibration method are systematically analyzed.The radiation characteristics of the sky and cement background in the 3mm and 8mm bands were simulated with different environmental parameters,atmospheric parameters,dielectric constants and physical geometrical characteristics.The background of the radiation modeling of metal stereo targets was established.(2)According to the basic principle of millimeter-wave radiation measurement,the method of binarization and ray-tracing are used to model the stereoscopic targets based on the theoretical model of traditional metal planar target radiation characteristics.The modeled apparent temperature was shown in the one-dimensional curves witch were compared with the measured results by 3mm and 8mm radiometers.Simultaneously,the millimeter-wave radiation images of metal sphere and metal column were measured by grid method.(3)The radiation characteristics of the typical shape metal objects are measured in fixed points in different background environments,such as the sea area in Chongming Island,the concrete in the campus and the absorbing material.The influence of the specific three-dimensional structures on the target radiation characteristics is analyzed.Furthermore,the experiment of external field radiation imaging was carried out for the metal objects with complex structures in different land backgrounds(grassland,sandy land,cement ground),and the edge information of the target was extracted by using active contour model algorithm.At the same time,an algorithm for fast extraction of target features is proposed based on the edge feature of the target image.The results show that the proposed algorithm can effectively extract the target feature information.The modeling and analysis of stereoscopic metal targets,the measurement in the laboratory,together with the measurement of different backgrounds in different fields(land and sea area)provide the theory and data support for the next step of metal targets identification and dynamic tracking.