| Terahertz electromagnetic radiation lies in the boundary region between microwave and optics band. Due to the shorter wavelength compared with microwaves, THz waves could handle ultra-broadband signals and narrow antenna beam. Meanwhile, the Doppler Effect is more obvious in THz band, which is beneficial for manoeuvrable targets detection and tracking. THz waves are transparent through many non-polar dielectric materials that are opaque in visible IR light. Owing to these advantages, THz technologies have been considered competitive methods for security, biomedical, remote sensing, communications and astronomy applications.In comparison with relatively well-developed technologies and widespread applications in microwave, mid-infrared, and optical bands, the scattering characteristics of THz wave cannot be described accurately by the traditional electromagnetic theory and optical theory. This brings new problems for the applications of THz technologies in radar target detection. The real-world applications in THz band are still in infancy, especially the immature manufacture techniques of frequency multiplier and mixer lead to the less-development of THz radar system and inadequately research and analysis of THz radar clutter and target characteristics. This also makes it difficult for the target detection with THz radar. Regarding the issue above, after surveying and analyzing traditional radar clutter and target characteristics, target detection methods, in this dissertation several key techniques of THz radar target detection are researched based on the measured data.The main work and contributions are summarized as follow:1. A survey of THz radar system, traditional radar clutter and target characteristics, target detection theory and methods is carried out. Combined with the feature of THz wave, the problems of applying THz technology on target detection are analyzed.2. For the statistical modeling of THz radar system and terrestrial clutter, a modeling method based on Mo LC is proposed. On the basis of statistical models of traditional clutter, the Mo LC method is utilized in the parameters estimation of THz radar system and terrestrial clutter. The statistical characteristics are determined by KL distance between models and measured data. For the features of non-homogeneous terrestrial clutter in THz band, the characteristics in range and time domain is respectively statistical modeled. The statistical characteristics of terrestrial clutter in THz band are validated.3. Considering that the target backscattering fluctuated tempestuously in THz band, the THz radar target backscattering measurement method based on ISAR imaging is proposed. This method take advantage of the short wavelength of THz wave and the small accumulation angle of ISAR imaging in THz band, reconstruct the target reflectivity map via small accumulation angle ISAR imaging, then the target backscattering at each observation angle can be extracted. The experimental results show that the proposed method can describe the fluctuation and statistical property of complex target backscattering in THz band.4. For the characteristics of target HRRP in THz band, a statistical modeling method with mono and mixture distribution models are proposed. The range cells are classified by target scattering centers. Range cells are modeled by mono or mixture distribution models. The Mo LC and DSEM are utilized in the parameters estimation. Experimental results show that the range cells’ statistical property of THz radar in different range resolutions can be modeled by the proposed method.5. Considering the features of THz wave, a distributed CFAR detection algorithm based on fusion center in THz band is proposed. This algorithm exploits the feature that it is easy to achieve narrow antenna beam with THz wave. The local CFAR detectors are designed evenly distributed on the circumference. The observation area is scanned by each local detector with narrow beam antenna, and the local two-dimensional detection results are obtained. Finally, the global two-dimensional detection result is obtained by the fusion center. Compared with mono CFAR detector, the performance is improved, and the coordinates of point target in observation area can be obtained. For the target detection with high resolution THz radar, the DSM-GLRT algorithm is utilized in THz range spread target detection. The performance in different resolution is analyzed with measured data.In summary, a series of studies are carried out centered on the problem of target detection in THz band. These studies provide theoretical and technical support for the application of THz technology in radar target detection.
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