A Study on Millimeter-Wave Imaging of Concealed Objects: Application Using Back-Projection Algorithm

Abstract

Abstract-Millimeter-wave (MMW) imaging is a powerful tool for the detection of objects concealed under clothing. Several factors including different kinds of objects, variety of covering materials and their thickness, accurate imaging of near-field scattered data affect the success of detection. To practice with such considerations, this paper presents the two-dimensional (2D) images of different targets hidden under various fabric sheets. The W-band inverse synthetic aperture radar (ISAR) data of various target-covering situations are acquired and imaged by applying both the focusing operator based inversion algorithm and the spherical back-projection algorithm. Results of these algorithms are demonstrated and compared to each other to assess the performance of the MMW imaging in detecting the concealed objects of both metallic and dielectric types.

A Near-Field 3d Circular Sar Imaging Technique Based on Spherical Wave Decomposition

“…Another method for processing CSAR data is the focusing operator (FO) algorithm which uses the focusing operator to compensate the altitude and the phase variations along the wave propagation path [4,19,20]. Due to the phase compensation operation for all pixels in scene, this algorithm has even lower computational efficiency than BP algorithm.…”

“…For processing near-field CSAR data, a common way is backprojection (BP) algorithm which is an extension of the computed tomography (CT) imaging in medicine [4,19]. In this algorithm, by calculating the distance from each radar azimuth to each scatterer in the scene, we can obtain the echo of each scatterer in different azimuth through any interpolation scheme.…”

“…They benefit from two advantages: firstly, some high frequency electromagnetic waves, such as millimeter waves (MMW) and terahertz waves (THz) can penetrate clothing or packages; secondly, microwaves are nonionizing and, therefore, microwave imaging systems are easily accepted by the public. These merits make microwave imaging systems have great potential in the field of concealed objects detection [4][5][6][7][8]. Besides detecting concealed objects in security check, microwave near-field imaging is also applied to non-destructive testing for quality compliance industrial procedures, images acquisition of vivo tissues for biological and medical studies and far-field radar cross-section (RCS) prediction with near-field measurement of target back-scattering properties [9][10][11][12].…”

Shape Feature Analysis of Concealed Objects With Passive Millimeter Wave Imaging

“…Millimeter wave (MMW) imaging has been widely adopted in security and military applications [1][2][3][4][5][6]. Passive MMW imaging can generate interpretable images under low visibility conditions such as fog, rain, dust, and smoke.…”

SUB-MILLIMETER WAVE FREQUENCY SCANNING 8 x 1 ANTENNA ARRAY

“…During the last decade, a large research effort has been dedicated to the development of sub-millimeter wave technology (300 GHz-3 THz), due to the large number of potential applications in different areas, such as terahertz imaging and sensing [1][2][3][4][5][6][7][8][9][10][11], wireless communications [12], radio-astronomy [13], fast measurement systems [14], non-destructive material analysis [15][16][17][18], or non-ionizing diagnosis [19][20][21][22], among others.…”