Near-field Millimeter-wave Imaging Technology Based On MIMO Array

In recent years, with the growing threat of terrorism, security inspection in public places such as airports, railway stations becomes increasingly important. Millimeterwave imaging has great application prospect in security inspection because it can penetrate common clothing, detect the concealed weapons and it has no ionizing radiation. With the demand of big imaging scene and high-resolution, the construction of radar imaging system will require a lot of antenna elements and transceiver channels. Hence the cost and complexity are increasing. In this paper, we propose a method of near-field MIMO array design, which is based on the principle of convolution and equivalent phase center and the principle of MIMO radar.Firstly, the basic principle and realization methods of radar imaging are introduced in this paper. Also, the near-field MIMO imaging process based on the assumption of target scattering center model is deduced.Secondly, the method of designing the near-field MIMO array is presented, which is based on the principle of equivalent phase center and convolution principle. And the feasibility of the MIMO sparse array is verified through analyzing and simulating the array factor directional pattern.Thirdly, a convolution back-projection algorithm for the near-field MIMO array imaging is improved. And a matched filter to compensate the phase error caused by using principle of equivalent phase center is presented, too. The disadvantage of this algorithm is the huge elapsed time of computing. Then, a new fast imaging algorithm based on the matrix completion theory is provided in this paper. And simulation results in different signal-noise ratio and the error between the reconstructed imaging and benchmark are provided to demonstrate the feasibility and efficiency of the algorithm.