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Localizing tunnel positions under rough surfaces with underground focused synthetic aperture radar

August 22, 2019 @ 3:00 pm - 4:00 pm

Co-sponsored by: IEEE MTT/AP Joint Chapter


Underground tunnels present both military and homeland security threats since smugglers use them as transit routes for trafficking weapons, explosives, people, drugs, and other illicit materials. Detecting and imaging the presence of tunnels in any given region of ground is possible because the air that fills them is materially quite different from anything else underground. Spotlight Synthetic Aperture Radar (SL-SAR) has been used to detect tunnels due to its ability to scan large areas of terrain in a short amount of time. In order to obtain strong and distinct target signals, underground focusing, based on ray refraction at the ground surface must be considered. This presents a challenge since the technique requires an estimation of the ground characteristics, and the random roughness of the soil surface tends to distort the reconstructed image of the analyzed geometry.

This presentation explores the impact of the surface roughness in underground focusing SAR imaging for tunnel detection applications. The study starts by simulating incident plane waves from 19 angles (-45 to 45 degrees) at 128 different frequencies (55 to 550 MHz) with 2-D Finite Difference Frequency Domain (FDFD) analysis on 2 different types of soil: non-dispersive sandy soil and lossy clay loam soil with 10 cm of randomly distributed roughness. It is demonstrated that a shallow tunnel can be imaged in low moisture, non-conductive sand, but that the more lossy moist clay presents too much surface clutter to distinguish the tunnel.


Prof. Carey M. Rappaport is a Fellow of the IEEE, and he received five degrees from the Massachusetts Institute of Technology (MIT): the S.B. degree in mathematics and the S.B., S.M., and E.E. degrees in electrical engineering in 1982, and the Ph.D. degree in electrical engineering in 1987. Prof. Rappaport has worked as a teaching and research assistant at MIT from 1981 to 1987 and during the summers at Communications Satellite Corporation Laboratories in Clarksburg, Maryland, and The Aerospace Corporation in El Segundo, California. He joined the faculty at Northeastern University in Boston, Massachusetts, in 1987 and has been a professor of electrical and computer engineering since July 2000. In 2011, he was appointed College of Engineering Distinguished Professor. During the fall in 1995, he was a visiting professor of electrical engineering at the Electromagnetics Institute of the Technical University of Denmark, Lyngby, as part of the W. Fulbright International Scholar Program. During the second half of 2005, he was a visiting research scientist at the Commonwealth Scientific Industrial and Research Organization in Epping, Australia.

He has consulted for CACI; Alion Science and Technology, Inc.; GeoCenters, Inc.; PPG, Inc.; and several municipalities on wave propagation and modeling, and microwave heating and safety. He was a principal investigator for the Army Research Office-sponsored Multidisciplinary University Research Initiative on Humanitarian Demining, a coprincipal investigator for the National Science Foundation-sponsored Engineering Research Center for Subsurface Sensing and Imaging Systems, and a coprincipal investigator and deputy director for the Department of Homeland Security-sponsored Awareness and Localization of Explosive Related Threats Center of Excellence.

Prof. Rappaport has authored more than 400 technical journal articles and conference papers in the areas of microwave antenna design, electromagnetic wave propagation and scattering computation, and bioelectromagnetics, and he has received two reflector antenna patents, two biomedical device patents, and four subsurface sensing device patents. As a student, he was awarded the AP-S’s H.A. Wheeler Award for best applications paper in 1986. He is a member of the Sigma Xi and Eta Kappa Nu professional honorary societies.

Room: 420
Bldg: 78
The University of Queensland
St. Lucia, Queensland


August 22, 2019
3:00 pm - 4:00 pm
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