Research On Millimeter Wave Radiation Characteristics And Imaging Of Typical Ground Objects

Compared with visible light and infrared,millimeter wave(MMW)has higher accuracy and penetrability when detecting targets all-weather and all-day,which makes it attracts extensive attention in detection,identification,investigation and tracking.The radiation characteristics of different targets are obvious,so the researches on the typical targets and metals have great application prospects.In terms of covert detection,the passive millimeter wave(PMMW)detection system has unique advantages due to its good concealment,small size and low cost,which makes it has greater application potential in military concealment and detection.There is still much room for the research of radiation characteristics and penetration depth of different target.Focusing on the radiation characteristics and the application scenarios of shallow-buried metal detection and imaging,the main research is as follows:(1)With the structure,principles and calibration method of MMW radiation analyzed,we simulated and measured the brightness temperature of sky and water.Several common MMW radiation imaging methods are also analyzed to show their advantages and disadvantages.(2)According to the basic principle of MMW radiometry,a 8mm-band dual-polarized radiometer and a calibration source are designed.Based on the radiation characteristics of typical objects,we collected and analyzed the data of characteristics of sky,water,vegetation to explore the polarization effect and enrich the radiation characteristics database.(3)Based on the analysis of the radiation model of the metal target,the temperature contrast of the antenna is calculated.In order to explore the effect of MMW imaging technology,the bare and shallow-buried metal plane are imaged.Furthermore,for the application scenario of shallow-buried metal detection,the three-layer medium model of sand is studied based on coherent and non-coherent method.Some experiments are also performed in the school to lay foundations for the subsequent field test.(4)In the aspect of shallow surface covert detection,combining theoretical analysis with experimental exploration,the field experiment of sand penetration characteristics was carried out in dongwazi,Nanjing to obtain the maximum depth of the buried metal plane that can be detected by MMW radiometer,so as to provide reference for subsequent experimental research.The related experimental attempts and data,solutions for improvement and existing problems lay the foundation for further research.