Millimeter-Wave Doppler Spectrum and Polarimetric Response of Walking Bodies

Abstract

In this paper, the Doppler spectra of the radar backscatter response of human body and a quadruped are presented at W-band frequencies. This study is motivated by the desire to utilize millimeter-wave radars to detect pedestrians against other targets in the radar scene. The approach is based on dissecting the radar backscatter to isolate the radar returns from different body parts. The forward model is based on an iterative physical optics approach. The complex motion of different parts of walking bodies and their amplitude and range of motion is directly reflected in their radar cross section (RCS) and Doppler spectrum bandwidth. It is shown that the Doppler spectra and RCS differences are sufficient to distinguish a walking human from stationary and other moving objects. Radar polarimetry in conjunction with time-frequency analysis is examined as a method for detecting concealed carried objects. The overall backscatter is decomposed into components associated with the limbs and torso which are then utilized to enhance target detection.Index Terms-Doppler effect, radar cross section (RCS), radar polarimetry.

Detection of moving human micro‐Doppler signature in forest environments with swaying tree components by wind

“…The scattered fields in human motion studies conventionally have been calculated using simple point scatterers to represent the different body parts [ Van Dorp and Groen , ; Ram et al ., ]. In Vahidpour and Sarabandi [] an iterative physical optics technique was utilized, which can be useful at high frequencies. However, these techniques do not include the mutual coupling effects between the different body parts.…”

Analysis of Moving Human Micro-Doppler Signature in Forest Environments

“…These, however, do not incorporate the mutual coupling effects between different human body parts. Another technique that has been employed is an iterative physical optics approach [34], which accounts for mutual coupling effects and can be useful only at very high frequencies, such as W-band. A full wave technique, such as the one employed in this paper, provides better accuracy for more complex structures but requires a large number of computational resources.…”

Concealed threat detection with the IRAD sub-millimeter wave 3D imaging radar

“…Threat objects scatter strongly into the cross-polar channel distinguishing them from blank subjects. 5. The spatial resolution of IRAD is just sufficient to resolve the shape of some threat objects.…”

“…Our approach, using the IRAD 340 GHz 3D imaging radar which has a more modest volumetric resolution [3], has concentrated on using polarization intensity information to identify signatures associated with concealed threats. It is well known that many threat objects exhibit strong cross-polar scattering which can distinguish them from human subjects [4,5]. A significant challenge for such radars is to operate them at high enough frame rates to cope with realistically dynamic scenes.…”