Abstract-Multipath is exploited to image targets that are hidden due to lack of line of sight (LOS) path in urban environments. Urban radar scenes include building walls, therefore creating reflections causing multipath returns. Conventional processing via synthetic aperture beamforming algorithms do not detect or localize the target at its true position. To remove these limitations, two multipath exploitation techniques to image a hidden target at its true location are presented under the assumptions that the locations of the reflecting walls are known and that the target multipath is resolvable and detectable. The first technique directly operates on the radar returns, whereas the second operates on the traditional beamformed image. Both these techniques mitigate the false alarms arising from the multipath while simultaneously permitting the shadowed target to be detected at its true location. While these techniques are general, they are examined for two important urban radar applications: detecting shadowed targets in an urban canyon, and detecting shadowed targets around corners.
Pillars represent some of the commonest supporting elements of modern and historical buildings. Non-destructive testing methods can be applied to gain information about the status of these structural elements. Among them, ground penetrating radar (GPR) is a popular diagnostic tool for the assessment of concrete structures. Despite several theoretical and experimental studies on concrete structural evaluation by GPR have been reported, little work has been done so far in relation to pillars. Owing to their circular geometry, pillars are complex multi-scattering environments, which render the interpretation of the radar images very challenging. This paper deals with the application of radio frequency tomography as a non-destructive technique for imaging the inner structure of pillars. The main goal of the study is the assessment of the imaging performance that can be obtained in comparison to conventional ground penetrating radar exploiting a multi-monostatic configuration. Accordingly, potentialities and performance of multimonostatic and multiview/multistatic measurement configurations are herein investigated in the inverse scattering framework. For each measurement configuration, the regularized reconstruction of a pointlike target and the spectral content are evaluated. The data inversion is carried out by means of the Truncated Singular Value Decomposition scheme. Tomographic reconstructions based on full-wave synthetic data are shown to support the comparative analysis.
Measurement results to validate the UTD triple diffraction coefficient are presented. The experimental setup consists of multiple metallic objects, with triangular and rectangular profiles, located inside an anechoic chamber and illuminated by a sector antenna to reproduce a spherical wavefront with a Transverse Electromagnetic (TEM) incident field. Another sector antenna is moved vertically to collect electromagnetic fields across the second order UTD Incident Shadow Boundaries and in the triple diffraction transition region. The measured and theoretical fields are compared using a free space normalization. Such comparison is also validated by calculating the mean error, the standard deviation, and root mean square error that occur between the theoretical model and the measured field. The results show excellent agreement between the theoretical third order UTD solution, employing the novel triple diffraction coefficient, and the experimental results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.