低频电磁波建筑物内部结构透视技术研究进展

在进入陌生建筑物内部之前获取其内部结构信息，能够为反恐作战、灾害救援等多种应用提供服务，具有重要的现实意义和研究价值。低频电磁波能够穿透常见建筑物材料传播，进而安全、稳定、隐蔽地获取墙后目标信息。利用低频电磁波获取墙后信息因此成为建筑物内部结构透视领域的研究重点。为获知该领域的发展脉络，并预测未来可能的发展趋势，该文对21世纪初以来该领域国内外公开文献进行了归纳总结。相关文献的梳理结果表明，利用低频电磁波进行建筑物内部结构穿透探测的技术目前主要包括3类:基于反射波测量的穿墙雷达成像技术、基于透射波测量的射频层析成像技术、基于多径信号的墙体位置估计技术。这3类技术均已取得一定具有实际意义的研究成果。该文围绕这3类技术所涵盖主要内容的发展历程进行了梳理，主要包括穿墙雷达墙后静止目标成像原理、基于穿墙雷达的建筑物内部结构观测模式、基于穿墙雷达成像的建筑物内部结构重建技术、基于射频层析成像的建筑物内部结构反演技术、基于多径信号的墙体位置估计技术，并以此对该领域的发展趋势进行了探讨。总结近20年以来低频电磁波建筑物内部结构透视技术的发展历程，可以发现建筑物内部结构穿透探测平台已由传统的机载、车载平台转向微型机器人、无人机等新型平台，而对应的建筑物内部结构信息重建方法，则由传统的雷达成像技术，发展成包含图像增强、稀疏重构等在内的多种新型方法。这些结果表明，建筑物内部结构透视技术正朝着系统化、多样化、智能化的方向发展。 

Advances on Penetrating Imaging of Building Layout Technique Using Low Frequency Radio Waves

Obtaining the internal layout of an unfamiliar building before entering the building has important practical significance and research value, as it can be applied for various services, such as anti-terrorism operations and disaster relief. Low-frequency electromagnetic waves can propagate through common building materials, and then the target information behind the wall is obtained safely and stably. Therefore, using low frequency radio waves to obtain the information behind the wall has become the research focus in the field of building layout reconstruction. To reveal the development context of this field and predict the possible future development trends, this paper summarizes the domestic and foreign public literature in this field since the onset of the 21st century. The results of the relevant literature indicate that the techniques of using low-frequency electromagnetic waves to reconstruct building layout currently include three types: through-the-wall radar imaging technology based on reflected wave measurement, radio-frequency tomography technology based on transmitted wave measurement, and wall position estimation technology based on multipath signals. These three technologies have achieved several practical research results. This article clarifies the development history of the main content covered by these technologies, which mainly includes the principle of through-the-wall radar imaging of stationary targets behind the wall, the observation mode of building internal structure based on through-the-wall radar, the reconstruction technology of building internal structure on the basis of through-the-wall radar imaging, the inversion technology of building internal structure on the basis of radio-frequency tomography, and the wall position estimation technology based on multipath signals. We also discuss the development trend of this field. In the past two decades, the development history of building layout penetrating imaging using low-frequency radio waves shows a change from the traditional airborne and vehicle-mounted building-layout-reconstruction platforms to new platforms such as microrobots and unmanned aerial vehicles. The corresponding reconstruction method has been developed from the traditional radar imaging technology to a variety of new methods, including image enhancement and sparse reconstruction. The results indicate that the building-layout-reconstruction technology is developing in the direction of systematization, diversification, and intelligence.