Research On 2-D Millimeter Wave Imaging Algorithm Based On Planar Scanning With Sparse Linear Array

In response to the increasing attack that threatens social stability, personnel surveillance is becoming more important. Thanks to the properties of good penetrability,millimeter wave is readily detect weapons and controband concealed by common clothing. Millimeter wave images can be very high resolution due to the relatively short wavelength. Comparing with conventional security survillance, such as mental detectors and X-ray systems, millimeter wave imaging technology can perceive more comprehensive and accurate information so that has more extensive application prospect,and will greatly improve inspection efficiency, this noncontact inspection is well suited for high-volume security checkpoints and pose no radiation hazard to health.The current millimeter wave imaging systems include two types, i.e. active and passive. The active millimeter wave imaging system is environmental insensitive and capable to reconstruct images with higher resolution than passive modality. More transceiver antennas always guarantee better resolution or shorter scanning time,however, higher costs will follow. A new plane scanning with sparse linear array proposed to handle this contradiction, which will availably decrease the costs of imaging systems due to a reduction in amount of antennas. The algorithm operated in W-frequency band to perform image reconstruction for targets with size no bigger than 2 m×1 m can perceive images with resolution of 4 mm to 5 mm detailed in this paper.The active millimeter wave imaging system and algorithm based on planar scanning with sparse linear array will be studied. Five main aspects are included.Introduced the development of active and passive millimeter wave imaging systems in China and abroad based on their applications to security inspection.Summarized the main technical difficulties and development trends areExpatiated the knowledge background of active millimeter wave imaging technology, focusing on the imagery theory and algorithm of holographic imaging systems.Introduced the sparse antenna array and explained how it works. Calibrated the phase error in every channel before sampling data, then designed an appropriate algorithm and revised the phase center error due to the separately distributed transmitting and receiving antennas.Studied the characteristics of sampled data, provided a simple method to process the data on non-equidistant grids. First homogenize the nonuniform data in the horizon direction and then apply NUFFT in one dimensional for data at vertical direction(orthogonal to the linear antenna array). This means will simplify the algorithm implementation and decrease the imaging error compared to traditional interpolation method.Made a conclusion in full. Proposed the forecast to the future research of the active imaging systems and algorithms according to the obtained knowledge during my postgraduate and the project study on the writing of this thesis.