Abstract
Terahertz (THz) imaging technology has received increased attention in recent years and has been widely applied, whereas the three-dimensional (3D) imaging for moving targets remains to be solved. In this paper, an adaptive 3D imaging scheme is proposed based on a single input and multi-output (SIMO) interferometric inverse synthetic aperture radar (InISAR) imaging system to achieve 3D images of moving targets in THz band. With a specially designed SIMO antenna array, the angular information of the targets can be determined using the phase response difference in different receiving channels, which then enables accurate tracking by adaptively adjusting the antenna beam direction. On the basis of stable tracking, the high-resolution imaging can be achieved. A combined motion compensation method is proposed to produce well-focused and coherent inverse synthetic aperture radar (ISAR) images from different channels, based on which the interferometric imaging is performed, thus forming the 3D imaging results. Lastly, proof-of-principle experiments were performed with a 0.2 THz SIMO imaging system, verifying the effectiveness of the proposed scheme. Non-cooperative moving targets were accurately tracked and the 3D images obtained clearly identify the targets. Moreover, the dynamic imaging results of the moving targets were achieved. The promising results demonstrate the superiority of the proposed scheme over the existing THz imaging systems in realizing 3D imaging for moving targets. The proposed scheme shows great potential in detecting and monitoring moving targets with non-cooperative movement, including unmanned military vehicles and space debris.
Highlights
Terahertz (THz) waves lie in the gap between microwave and infrared, their frequency generally covers the band from 0.1 THz to 10 THz, corresponding to a wavelength from 3 mm to 30 um
In the reported research so far, high-resolution inverse synthetic aperture radar (ISAR) images of the moving targets on a turntable are obtained with THz radar systems, where the targets are resolved in the cross-range direction by exploiting the Doppler frequency induced by angular rotation of the targets
With a combined motion compensation method proposed in this paper, focused and coherent ISAR images of the moving targets can be achieved by each receiving channel
Summary
Terahertz (THz) waves lie in the gap between microwave and infrared, their frequency generally covers the band from 0.1 THz to 10 THz, corresponding to a wavelength from 3 mm to 30 um. In the reported research so far, high-resolution ISAR images of the moving targets on a turntable are obtained with THz radar systems, where the targets are resolved in the cross-range direction by exploiting the Doppler frequency induced by angular rotation of the targets. University of Defense Technology (NUDT) developed an interferometric inverse synthetic aperture radar (InISAR) imaging system in the 0.22 THz band [26,27], and achieved 3D images of targets undergoing turntable rotation or equivalent translational movement. A 3D adaptive imaging scheme for non-cooperative moving targets is proposed based on an InISAR system in the 0.2 THz band. With a combined motion compensation method proposed in this paper, focused and coherent ISAR images of the moving targets can be achieved by each receiving channel.
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