The Research On Wide-band Microwave Holographic Imaging Algorithm Applied To Shallow Target Detection

As a kind of noninvasive imaging technology with high resolution,microwave holography can be widely used in modern social life of municipal construction,social security and nondestructive testing.This thesis focused in the application of shallow target detection of this technology.For different objects and imaging environment,this thesis mainly studied a variety of imaging algorithm.On the basis of theoretical research,this thesis finally achieved the detection of shallow target through simulation and experiment.The narrow-band imaging algorithm is widely used for shallow targets detection.For multi-objective and complex environment detection,the only use of single frequency signal has a limitation.The aliasing effect will make it difficult to get the accurate information of target.To avoid the limitation of the single-frequency imaging algorithm in range resolution,a two-frequency microwave holographic imaging algorithm is presented.For this algorithm,the target is illuminated by two close frequencies rather than single frequency.The range resolution can be improved by the utilization of Gaussian phase information.Wideband imaging algorithm is proposed to further improve the quality of the target imaging.The target echo data can be gotten by launching broadband continuous wave towards the target.Then the data will has a phase compensation in the spatial frequency domain.The three-dimensional image of the target can be gotten by IFFT.We can get depth and shape information of the target through the image.The probability of target detection can also be improved.Based on the algorithm theory,Matlab was used to verify the effectiveness and robustness of the algorithm.Further more,the experiment data was used to reconstruct the image of the target.The experimental results show that the range aliasing effect can be weakened by using the wideband imaging algorithm.The image resolution can also be improved.