Evaluation of TRM in the Complex Through Wall Environment

Abstract

Abstract-Practical interests arising from behind-the-wall target detection, surveillance and reconnaissance et al. claim for high capability of imaging in complicated environments. Time Reversal Mirror (TRM) technique, making use of the principle of reciprocity, emerges as a promising way to deal with such complex problem. In this paper, we investigate TRM in the ultra-wideband (UWB) through wall radar imaging (TWRI) through numerical simulation. The probing region is a square room, with walls of rough surface and random media parameters. TRM is used to image the target settled in the room. We evaluate the degradation of the images when the aperture of the array is decreased or the received signals are contaminated by noises. The back projection (BP) algorithm is employed here as a comparison for imaging quality. For the case in which the random walls are changed between the forward and inverse phase of time reversal, we check the imaging stability and applied an averaged Green's function to improve the imaging quality. Finally, some interesting conclusions are drawn.

Moving Target Tracking Using Time Reversal Method

“…In [17] the effect of acoustic source motion on focusing has been taken into consideration. For the point source f (t) with constant speed v the time reversed field is…”

“…The capability of time reversal method in focusing waves attracts many applications ranging from remote sensing, imaging or wireless communication [3][4][5][6][7][8][9][10][11]. Since the need for tracking of moving targets in strongly cluttered environments arises in many radar applications, including intruder detection systems and through the wall microwave imaging [12][13][14][15][16][17][18][19][20], the effect of source motion on time reversal focusing is critical. In this paper, we address the problem of time reversal focusing of electromagnetic waves in case of moving source.…”

Time Reversal Experiments in the Microwave Range: Description of the Radar and Results

“…The RF front-end is made of a linear array of 8 UWB antennas plus one more spare antenna working in a multistatic configuration. Antennas are antipodal symmetric Exponentially Tapered Slot Antennas (ETSA), printed on a Duroid substrate of permittivity r = 2.2 and dimensions 8 cm × 8 cm; they show very good input impedance matching (SWR < 2) in the [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] GHz frequency band and radiate a vertically-polarized (perpendicular to the plane of Fig. 1) electric field [29].…”

“…Recently, particular attention has been devoted to the application of TR techniques in the ultrawideband regime for telecommunications [7,8] and for detection of targets in the through-the-wall framework [9,10]. Generally speaking, two different instrumental approaches can be distinguished among the published experiments.…”

Through-Wall Imaging: Application of Subspace-Based Optimization Method

“…It has a variety of practical applications including fire rescue, emergency relief, and military operations. To our knowledge, such imaging problem has been approached in two ways: Some employed SAR processing methods and appropriately modified them in order to account for the presence of walls [1,2]; others cast the imaging problem into an inverse scattering problem governed by wave equations [3][4][5][6]. In either case, it is well known that such inverse problem is nonlinear and ill-posed.…”