Research On Millimeter Wave Aperture Coded Imaging

Aperture-coded radar imaging is a new system of real-aperture microwave imaging technology.Millimeter wave aperture coded imaging learns from the basic principles of microwave-associated imaging and optical aperture-encoded imaging.It uses different frequencies electromagnetic waves to embrave metamaterial antenna or random masks and other coded antennas to change the amplitude and phase distribution of the scattering field in the scene region to achieve high-resolution imaging.It has the advantages of high resolution and high frame rate,and is one of the important development trends of real aperture radar imaging technology.The optical aperture coding is light field modulation,and the idea is applied to the radar field to be antenna pattern modulation.The aperture coded imaging theory aims to achieve electromagnetic wave pattern and wavefront spatial random modulation.Drawing on the idea of microwave correlation imaging,the imaging method forms a 2D randomly distributed radiation field in the detection region.The spatial radiation field is the perceptual matrix in imaging theory,also known as sparse dictionary.The diversified illumination mode acts on the scene space,and the echo detector can receive echoes with rich degrees of freedom to carry the target geometric features.The richer the illumination mode,the greater the potential of super-resolution imaging,which will greatly reduce the dependence of imaging on the relative motion of the radar and the target.Aperture coding consists of two main components,the coding aperture design and the echo signal processing algorithm.A single-channel detected echo signal is processed using computational imaging techniques to reconstruct a 3D microwave image of the scene or target.The aperture coding system radar has wide application prospects in missile seeker front view imaging,unmanned platform environment sensing,and planetary detector environment sensing.The main research contents of this paper are the imaging model construction,the two-dimensional imaging simulation,and the hardware implementation of the echo processing algorithm of the aperture coding system radar,it does not do much research on the aperture coding design,compressed sensing algorithm selects Tw IST and OMP.The content of the article is as follows,Firstly introducing the theoretical basis of aperture coding imaging,and demonstrate the significance of aperture coding method in the field of radar imaging.The pattern characteristics of aperture coded radar are simulated by phased array.Reconstructing the target scattering center using echo signals is a pathological inversion process.Using the theory of compressed sensing,the regularization method and the sparse reconstruction algorithm are used to implement this process.Based on the above research,the 2D imaging simulation experiment is carried out by using the sparse dictionary constructed in this paper.The metamaterial aperture imaging radar is an important implementation mode of the aperture coding system radar.In this paper,the scenes is directly imaged by the measured metamaterial antenna pattern,to verify its imaging mechanism.Aiming at the technical problem that the aperture coded radar has large data volume and large matrix dimension,which leads to long running time and large computational complexity of imaging algorithm,this paper designs a fast implementation method of FPGA-based Tw IST algorithm.Using Xilinx's VC709 board to complete the FPGA implementation of the aperture coded radar echo processing algorithm(Tw IST),the algorithm's operating efficiency is significantly improved compared to the PC,and the parallel acceleration of the echo processing algorithm is realized,taking an important step in the realization of imaging theory to engineering.The hardware simulation of two-dimensional(azimuth-pitch dimension)aperture coding radar is carried out,and the acceptable reconstruction results can be obtained,which directly verifies the correctness and rationality of Verilog programming.