Research And Design Of Near Field Imaging Algorithm For Terahertz Radar Based On MIMO Array

As a newly developed technology in the past decades,terahertz technology has been gradually researched and used for various theoretical exploration and life applications,including measurement of electromagnetic properties of materials,use of medical equipment,and non-invasive depth detection.The most closely related to military and civilian use is terahertz radar imaging.At present,most of the imaging algorithms used in terahertz radar are still based on radar imaging algorithms in the microwave or optical frequency bands.Also,the particularity of the terahertz band requires us to develop an algorithm for independent adaptation of the electromagnetic wave characteristics of this band.And the most important one of them is the imaging processing corresponding to the terahertz near-field measurement environment.Due to the power limitations of terahertz devices and the complexity of the near-field environment,terahertz near-field imaging algorithms need to be adapted to the terahertz near-field environment based on traditional radar imaging algorithms.Therefore,this will be based on the terahertz radar near-field test environment,based on the traditional algorithm to improve,so as to adapt to the near-field imaging of terahertz radar.Based on the MIMO technology,the equivalent experiment is designed to measure,thus completing the data acquisition and reconstruction,and providing data support and theoretical derivation for the development of the later MIMO array.The main research contents and work of this are as follows:(1)Based on two traditional microwave radar imaging algorithms,Back Projection(BP)and Range Migration(RM)imaging algorithms,it is improved to be suitable for terahertz radar near-field imaging environment.The measurement of the target is achieved by a virtual array measurement method to equivalent the MIMO array.(2)The differences between the two imaging algorithms in terahertz near-field imaging are compared.Contrast and summarize from the imaging principle and imaging results.The advantages and disadvantages of the two imaging algorithms in terahertz near-field imaging are obtained.The causes of the differences were analyzed and quantitatively calculated to prepare for later algorithm improvements.(3)Making fuse of these two algorithms.Getting each algorithms' advantage with a little computing time.After fusion,we can get better imaging results.(4)By comparing the synthetic aperture radar imaging algorithm and the focal plane imaging results,the advantages and disadvantages of the two imaging methods are obtained.The experimental data proved the difference between the two imaging methods in 2D and 3D reconstruction.The two imaging methods are summarized and provide a reference for later imaging experiments.