近场毫米波成像和散射体电磁参数提取的研究
发布时间：2019-02-18 07:44
【摘要】：为了满足日益迫切的安防需要,新型成像系统大多采用了毫米波成像技术。本文从成像算法的理论基础入手,采用近场毫米波SAR成像的技术,系统地推导其成像算法公式、对毫米波成像算法进行系列仿真验证、并对散射物体的电磁参数的获取和成像系统平台构建等方面进行了深入研究。论文主要研究工作如下:(1)研究了基本的毫米波成像理论研究了SAR成像技术的原理、工作模式及其分辨率。研究了毫米波成像的理论基础,分别推导了单频点和宽带成像两种情形下的毫米波全息成像算法,并分析了采样间隔及分辨率等图像重建参数。(2)柱面毫米波SAR成像及其仿真验证针对近场条件,系统地推导了柱面毫米波SAR成像算法的公式,研究了不同分辨率情况下的系统带宽、最大频率间隔以及最大角度间隔之间的相互关系。利用金属平板的仿真成像,分析了接收天线阵元角度间隔和系统带宽对成像分辨率的影响。仿真实现了多种形状、金属及非金属材质的电磁逆散射成像,算法能较好的对其实现图像重建。仿真实现了人体携带隐匿物品的成像,利用成像算法可明显区分人体及有耗介质。(3)提出了基于毫米波SAR成像的电磁参数提取方法基于毫米波SAR成像方法,利用介质体的相对介电常数与自由空间不同和电磁波在不同介质体内的传播速度的变化,提出了基于毫米波SAR成像的电磁参数提取方法,并进行了仿真验证。对不同的无耗介质及有耗介质,所提取的相对介电常数偏差在15%左右。(4)近场毫米波SAR成像系统构建设计并构建了近场毫米波SAR成像平台的系统,分别在2GHz~18GHz,17GHz~26.5GHz不同的频段下,对金属板、铝罐(含液体)、金属与木块混合体进行了实际测试和图像重建,最终的成像结果与仿真结果吻合,与预期效果相近。验证了仿真结果的正确性以及算法的可行性,也验证了成像系统的正确性。
[Abstract]:In order to meet the urgent need of security, most of the new imaging systems adopt millimeter wave imaging technology. This paper starts with the theoretical foundation of the imaging algorithm, uses the near-field millimeter wave SAR imaging technology, systematically deduces its imaging algorithm formula, and carries on a series of simulation verification to the millimeter wave imaging algorithm. The acquisition of electromagnetic parameters of scattering objects and the construction of imaging system platform are studied in detail. The main work of this paper is as follows: (1) the basic millimeter wave imaging theory is studied. The principle, working mode and resolution of SAR imaging technology are studied. The theoretical basis of millimeter-wave imaging is studied, and the millimeter-wave holographic imaging algorithms for single-frequency and wideband imaging are derived, respectively. The image reconstruction parameters such as sampling interval and resolution are analyzed. (2) Cylindrical millimeter wave SAR imaging and its simulation verify that the formula of cylindrical millimeter wave SAR imaging algorithm is systematically derived for near-field conditions. The relationship among system bandwidth, maximum frequency interval and maximum angular interval is studied at different resolution. In this paper, the influence of angle interval of receiving antenna array and system bandwidth on imaging resolution is analyzed by using the simulation imaging of metal plate. Electromagnetic inverse scattering imaging of various shapes, metals and non-metallic materials is realized by simulation, and the algorithm can be used to reconstruct the images. Simulation has realized the imaging of human body carrying hidden objects, and the imaging algorithm can be used to distinguish the human body from the lossy medium. (3) the method of extracting electromagnetic parameters based on millimeter wave SAR imaging is proposed based on millimeter wave SAR imaging method. A method of extracting electromagnetic parameters based on millimeter wave SAR imaging is proposed, which is based on the variation of the relative dielectric constant of the dielectric body and the free space and the velocity of electromagnetic wave propagating in different media. The method is verified by simulation. For different lossless media and lossy medium, the relative dielectric constant deviation is about 15%. (4) the near-field millimeter wave SAR imaging system is designed and constructed, and the system of near-field millimeter wave SAR imaging platform is designed and constructed at 2GHz ~ (18 GHz), respectively. Under different frequency bands of 17GHz~26.5GHz, the mixture of metal plate, aluminum tank (containing liquid), metal and wood block were tested and reconstructed. The final imaging results are in good agreement with the simulation results and are similar to the expected results. The correctness of the simulation results and the feasibility of the algorithm are verified, and the correctness of the imaging system is also verified.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.52
本文编号：2425627
[Abstract]:In order to meet the urgent need of security, most of the new imaging systems adopt millimeter wave imaging technology. This paper starts with the theoretical foundation of the imaging algorithm, uses the near-field millimeter wave SAR imaging technology, systematically deduces its imaging algorithm formula, and carries on a series of simulation verification to the millimeter wave imaging algorithm. The acquisition of electromagnetic parameters of scattering objects and the construction of imaging system platform are studied in detail. The main work of this paper is as follows: (1) the basic millimeter wave imaging theory is studied. The principle, working mode and resolution of SAR imaging technology are studied. The theoretical basis of millimeter-wave imaging is studied, and the millimeter-wave holographic imaging algorithms for single-frequency and wideband imaging are derived, respectively. The image reconstruction parameters such as sampling interval and resolution are analyzed. (2) Cylindrical millimeter wave SAR imaging and its simulation verify that the formula of cylindrical millimeter wave SAR imaging algorithm is systematically derived for near-field conditions. The relationship among system bandwidth, maximum frequency interval and maximum angular interval is studied at different resolution. In this paper, the influence of angle interval of receiving antenna array and system bandwidth on imaging resolution is analyzed by using the simulation imaging of metal plate. Electromagnetic inverse scattering imaging of various shapes, metals and non-metallic materials is realized by simulation, and the algorithm can be used to reconstruct the images. Simulation has realized the imaging of human body carrying hidden objects, and the imaging algorithm can be used to distinguish the human body from the lossy medium. (3) the method of extracting electromagnetic parameters based on millimeter wave SAR imaging is proposed based on millimeter wave SAR imaging method. A method of extracting electromagnetic parameters based on millimeter wave SAR imaging is proposed, which is based on the variation of the relative dielectric constant of the dielectric body and the free space and the velocity of electromagnetic wave propagating in different media. The method is verified by simulation. For different lossless media and lossy medium, the relative dielectric constant deviation is about 15%. (4) the near-field millimeter wave SAR imaging system is designed and constructed, and the system of near-field millimeter wave SAR imaging platform is designed and constructed at 2GHz ~ (18 GHz), respectively. Under different frequency bands of 17GHz~26.5GHz, the mixture of metal plate, aluminum tank (containing liquid), metal and wood block were tested and reconstructed. The final imaging results are in good agreement with the simulation results and are similar to the expected results. The correctness of the simulation results and the feasibility of the algorithm are verified, and the correctness of the imaging system is also verified.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.52
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