Theory And Method Of Perspective Microwave Tomography Of Building Layout Structure

In a sheltered urban environment,microwave signals can be used to see through obstacles such as walls,detect unknown blind areas,and realize indoor target positioning,tracking,identification,building layout imaging,etc.This has important application prospects in disaster rescue,anti-terrorism,and urban warfare.When microwave signals interact with the building environment,complex electromagnetic propagation phenomena such as transmission,reflection,and diffraction will occur,resulting in physical effects such as clutter and blurring of echo signals.How to efficiently utilize complex echo signals to achieve high-precision building layout imaging is a research hotspot and difficulty at home and abroad.Focusing on the imaging problem of building layout structure,this dissertation conducts research on the theory and method of perspective microwave tomography of building layout structure,including single-frequency microwave tomography method under narrow beam signal,single-frequency microwave tomography method under wide beam signal,dual-frequency fusion building layout tomography method,etc.The main work and innovations of the dissertation are listed as follows:1.The transmission and diffraction characteristics of the electromagnetic wave in different building structure scenes are analyzed,and the Wentzel-Kramers-Brillouin(WKB)signal model based on linear approximation under narrow-beam microwave signal and the Rytov signal model based on electromagnetic beam direction graph constraint under wide-beam microwave signal are established.2.A microwave tomography optimal method based on region segmentation is proposed.First,based on the analysis of the imaging mechanism of Radon projection transformation,the intrinsic correlation representation between microwave tomographic sampling angles and building layout imaging is derived.Then,the imaging area is segmented by image edge detection or seed growing algorithm.Finally,the building layout image is obtained by fusing the adaptive binarization results of each sub-region,which solves the problem of object imaging expansion under the condition of sparse sampling in the analytical imaging algorithm.3.An iterative imaging method for microwave tomography based on prior information constraints is proposed.The iterative initial value is constructed using the filtered back-projection imaging algorithm.In the iterative solution process,the relative permittivities of the objects in the building scene are utilized as the prior information to construct a prior information-constrained optimization equation,which realizes the highprecision imaging of multi-media building scenes and improves computing efficiency.4.A microwave tomographic statistical imaging method based on wide-beam signal is proposed.First,by constructing the maximum likelihood function of the imaging matrix of the building layout,the statistical imaging equation is derived.Then the imaging matrix is updated by the sparse angle-dependent subset data,which realizes the microwave tomography of the building layout under wide-beam signal.5.A microwave tomography method for building layout based on dual-frequency fusion is proposed.First,the differences in the propagation characteristics of different frequency signals are theoretically analyzed.Then,the joint iterative imaging algorithm under the total variation constraint is utilized to obtain building layout images of different frequency signals.Finally,by incoherently fusing sub-images,the problems of building edge blur and artifacts in single-frequency signal images are solved,and the imaging accuracy is improved.The proposed models and methods above have been verified by numerical simulations and radar test data,which shows that the above methods can realize microwave tomography of building layout under different conditions.