Impulse radar imaging system for concealed object detection
Impulse radar imaging system for concealed object detection
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用于隐藏物体检测的脉冲雷达成像系统
DOI：
10.1117/12.2029462
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Podd F
中科院分区：
文献类型：
--
作者：
Podd F
用于在检查站对隐藏物体进行成像的电磁系统通常采用毫米和太赫兹频率的辐射。这些系统已被证明是有效的，并提供了足够高的分辨率图像。然而，存在困难，并且当前的电磁系统具有限制，特别是在基于形状、表面发射率或反射率（其是指示性参数）准确区分威胁和无害物体方面。此外，水在毫米波长和太赫兹频率下的吸收系数很高，这使得这些频率更难以通过厚厚的潮湿衣服成像。本文认为，在低千兆赫范围内使用超宽带（UWB）的潜力。将该频带应用于安全检查似乎是一个相对较新的领域。由于最近可获得在这些频率下工作的低成本集成电路，实现UWB系统的商业案例在财政上是可行的。虽然是为通信领域设计的，但这些设备也可以执行所需的UWB雷达测量。本文报道了一种2 ~ 5GHz带宽的线阵扫描器的实现。本文介绍了发射和接收天线阵列的设计和制造，其个别元素是一种对映Vivaldi天线。在CST微波工作室中模拟了天线的频率和角度响应，并与实验室测量结果进行了比较。为了提高图像质量，采用了背景减除和反卷积的数据预处理方法。背景减除方法使用参考数据集来从数据集中去除天线串扰和房间反射。去卷积方法使用维纳滤波器来“锐化”返回的回波，这提高了重建图像的分辨率。滤波器使用脉冲响应参考数据集和信噪比参数来确定如何对回波数据集中包含的频率进行归一化。所选择的图像重建算法是基于反投影方法。该算法在MATLAB中实现，并使用预先计算的灵敏度矩阵，以提高计算速度。结果包括2D和3D图像数据集。通过在测试对象上扫描双十六元件线性天线阵列来获得3D数据集。该系统已在人类和人体模型测试对象上进行了测试。放置在人体/人体模型躯干上的物体的前表面是清晰可见的，但其存在也可以从指示性成像特征中看到。该特性是由电磁辐射穿过对象时波速的降低引起的，并且表现为重建图像中容易识别的压痕。原型系统已被证明可以轻松检测隐藏在衣服下的12 mm x 30 mm x 70 mm塑料物体。
Electromagnetic systems for imaging concealed objects at checkpoints typically employ radiation at millimetre and terahertz frequencies. These systems have been shown to be effective and provide a sufficiently high resolution image. However there are difficulties and current electromagnetic systems have limitations particularly in accurately differentiating between threat and innocuous objects based on shape, surface emissivity or reflectivity, which are indicative parameters. In addition, water has a high absorption coefficient at millimetre wavelength and terahertz frequencies, which makes it more difficult for these frequencies to image through thick damp clothing. This paper considers the potential of using ultra wideband (UWB) in the low gigahertz range. The application of this frequency band to security screening appears to be a relatively new field. The business case for implementing the UWB system has been made financially viable by the recent availability of low-cost integrated circuits operating at these frequencies. Although designed for the communication sector, these devices can perform the required UWB radar measurements as well. This paper reports the implementation of a 2 to 5 GHz bandwidth linear array scanner. The paper describes the design and fabrication of transmitter and receiver antenna arrays whose individual elements are a type of antipodal Vivaldi antenna. The antenna’s frequency and angular response were simulated in CST Microwave Studio and compared with laboratory measurements. The data pre-processing methods of background subtraction and deconvolution are implemented to improve the image quality. The background subtraction method uses a reference dataset to remove antenna crosstalk and room reflections from the dataset. The deconvolution method uses a Wiener filter to “sharpen” the returned echoes which improves the resolution of the reconstructed image. The filter uses an impulse response reference dataset and a signal-to-noise parameter to determine how the frequencies contained in the echo dataset are normalised. The chosen image reconstruction algorithm is based on the back-projection method. The algorithm was implemented in MATLAB and uses a pre-calculated sensitivity matrix to increase the computation speed. The results include both 2D and 3D image datasets. The 3D datasets were obtained by scanning the dual sixteen element linear antenna array over the test object. The system has been tested on both humans and mannequin test objects. The front surface of an object placed on the human/mannequin torso is clearly visible, but its presence is also seen from a tell-tale imaging characteristic. This characteristic is caused by a reduction in the wave velocity as the electromagnetic radiation passes through the object, and manifests as an indentation in the reconstructed image that is readily identifiable. The prototype system has been shown to easily detect a 12 mm x 30 mm x70 mm plastic object concealed under clothing.
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具有测量噪声的成像的宽带分辨率分析。
影响因子：
1.9
作者：
A. Fannjiang;K. Sølna
通讯作者：
K. Sølna
DOI：
--
发表时间：
2008
期刊：
2008 Mosharaka International Conference on Communications, Propagation and Electronics
影响因子：
--
作者：
N.H. Mohammad;W. Ismail
通讯作者：
W. Ismail
DOI：
--
发表时间：
2009
期刊：
影响因子：
--
作者：
Lu Guo
通讯作者：
Lu Guo
凹口天线
DOI：
--
发表时间：
2004
期刊：
影响因子：
--
作者：
R. Lee
通讯作者：
R. Lee
DOI：
--
发表时间：
2010
期刊：
影响因子：
--
作者：
S. Harmer;David Andrews;N. Rezgui;N. Bowring
通讯作者：
N. Bowring