Full Polarimetric Step Frequency Ground Penetrating Radar And Freeman Polarimetric Decomposition Technology

Ground penetrating radar(GPR)is widely used in non-destructive shallow geophysical exploration technology which applies the propagation and reflection theory of the high-frequency electromagnetic waves.With the rapid development of electronic technology,the requirements for the quality of data and the amount of information carried by polarimetric ground penetrating radar have continuously increased in production,life,and scientific research.Due to the introduction of a large number of data processing methods,the GPR data processing gap was filled.The Polarimetric radar has received more and more attention due to its certain advantages in filtering and enhancing the target signal,anti-active and anti-clutter interference,target detection and recognition.In order to efficiently complete the data acquisition under different terms modes,as much as possible to obtain the information of the detection target,the GPR system is gradually moved from the original single-pair antenna,that is,the single-polarimetric mode antenna To the multiple-polarimetric mode antenna combination direction to meet the need for rich target feedback information in actual exploration.However,if the antenna arrays are arranged in different stages in different polarimetric modes,it will not only take time and labor to affect the detection efficiency,but also be affected by the accuracy of the antenna's repetitive positioning.It will introduce a huge error to the detection work in different degrees.If we can complete the arrangement work of multiple polarized mode antenna combinations at one time,the work efficiency will be greatly improved.Polarimetric decomposition technology has been well-developed and applied in the field of remote sensing research.The polarimetric data obtained through detection can be used to distinguish different target objects with extremely high accuracy.In recent years,some researchers in the field of ground penetrating radar have introduced polarimetric decomposition technology into the research of ground penetrating radar.Using polarimetric decomposition technology to process target volume data in the exploration of ground penetrating radar has also achieved good results.For practical work,more effective methods are needed to enhance the recognition effect.We develop the full polarimetric step frequency ground penetrating radar and to study on polarimetric target decomposition technology.The full text is divided into six chapters: Chapter OneThe development history and status of frequency-domain ground penetrating radar and polarimetric ground penetrating radar are analyzed.The research status of polarimetric decomposition technology is summarized.The problems to be solved in this paper,research contents and research innovation points are proposed.Chapter TwoBased on the description of the antenna theory,the HFSS simulation software was used to simulate and optimize four antennas commonly used in ground penetrating radar.By analyzing the characteristics of different antennas,we choose Vivaldi antenna to perform and test as the antenna element of the antenna array.Two antenna arrays are established,including HH and VV co-polarimetric modes and HV and VH cross-polarimetric modes.,which called multiple coverage full polarimetric antenna array and full polarimetric common-point antenna array.Chapter ThreeThe full polarimetric step frequency ground penetrating radar was developed.The two channels of the vector network analyzer were extended to six channels through switch-controlled converters and coaxial switches.Based on the Labview development platform,the data acquisition and control system were designed and developed to realize the automatic control.Polarimetric data acquisition is performed on the metal plane plate and the metal dihedron respectively and the response profile can verify the theoretical results.Chapter FourDescribe the theoretical basis of polarimetric property analysis technology.Compared with the traditional single polarimetric theory,a new data analysis theory used in polarimetric ground penetrating radar was developed.It can extract the scattering matrix,feature vector,polarimetric coherent matrix and polarimetric covariance matrix of the underground target.Chapter FiveBy merging model-based Freeman polarimetric decomposition technique with the migration equation on all-polarimetric data,we develop a new polarimetric decomposition analysis method.Apply this method to the full polarimetric ground penetrating radar data to obtain subsurface target imaging by migration and color-coded polarimetric information.Subsurface targets can be classified and high-quality target images can be reconstructed to extract surface target attributes.Three-dimensional polarimetric data of four standard targets were collected in the laboratory,and four polarimetric targets were used to classify the targets to verify the feasibility of the method.Chapter SixConclusion and outlook.The main contributions of this study are as follows:(1)Using the HFSS simulation software to simulate and optimize the four antennas of the ground penetrating radars.By comparing the characteristics of different antennas in the same frequency band,we choose Vivaldi antenna to optimize,test and used as the antenna element of the antenna array.(2)Design and construct a multiple-coverage full polarimetric antenna array and a full polarimetric common-point antenna array.The former one improves signal-tonoise ratio by overlaying CMP data,the latter one which consist of a small number of antenna elements can obtain a common-point data including four polarimetric modes.(3)Develops the full polarimetric step frequency ground penetrating radar.We extended the dual channels to six channels through switch-controlled converters and coaxial switches.A data acquisition and control system were designed and developed based on the Labview development platform.We can control all the apartment of the system by operation the user interface.The application experiment was performed to verify the radar hardware and software system and the two antenna array systems.(4)Develops a new polarimetric decomposition analysis method which merging the model-based Freeman with the migration technique.Apply this method to obtain subsurface target imaging by migration and color-coded polarimetric information.It can improve the classification capability of GPR for the subsurface target to use both the geometrical feature and polarimetric information.(5)Develops a data analysis theory for full polarimetric ground penetrating radar,which can be applied to the data analysis method of full polarimetric ground penetrating radar.It can extract the scattering matrix,feature vector,polarimetric coherent matrix and polarimetric covariance matrix of the underground target.