Through-Wall Imaging Using Low-Cost Frequency-Modulated Continuous Wave Radar Sensors

Abstract

Many fields of human activity benefit from the ability to create images of obscured objects placed behind walls and to map their displacement in a noninvasive way. Usually, imaging devices like Synthetic Aperture Radars (SARs) and Ground-Penetrating Radars (GPRs) use expensive dedicated electronics which results in prohibitive prices. This paper presents the experimental implementation and the results obtained from an imaging system capable of performing SAR imaging and interferometric displacement mapping of targets located behind walls, as well as 3D GPR imaging using a low-cost general-purpose radar sensor. The proposed solution uses for the RF section of the system a K-band microwave radar sensor module implementing Frequency-Modulated Continuous Wave (FMCW) operation. The low-cost sensor was originally intended for simple presence detection and ranging for domestic applications. The proposed system was tested in several scenarios and proved to operate as intended for a fraction of the cost of a commercial imaging device. In one scenario, it was able to detect and locate a 15 cm-diameter fire-extinguisher located at a distance of 3.5 m from the scanning system and 1.6 m behind a 3 cm-thick MDF (medium-density fiberboard) wall with cm-level accuracy. In a second test, the proposed system was used to perform interferometric displacement measurements, and it was capable of determining the displacement of a metal case with sub-millimeter accuracy. In a third experiment, the system was used to construct a 3D image of the inside of a wood table with cm-level resolution.

Real-Time Synthetic Aperture Radar Imaging with Random Sampling Employing Scattered Power Mapping

“…Although the computation in (10) requires the 2D FT of the PSFs, it is orders of magnitude faster than its real-space counterpart in (9) [77]. Moreover, it is the k-space PSF maps that are needed for the efficient deconvolution of (7) and the recovery of the reflectivity function ρ(r ′ ), as explained next.…”

“…In recent years, many microwave and millimeter-wave (mm-wave) imaging technologies have emerged to cater to a multitude of applications based on the principles of synthetic aperture radar (SAR). These innovative applications span various domains such as nondestructive testing and evaluation (NDT&E) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], security inspection [ 8 , 9 , 10 , 11 , 12 , 13 ], and medical imaging [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Revolutionizing aerial surveillance, small unmanned aerial vehicles (UAVs) emerge as pivotal players in SAR imaging [ 21 , 22 , 23 , 24 , 25 , 26 ].…”