Friday,  21 October 8:00 AM - 12:00 Noon Lincoln Room

Phased Arrays for Nearfield Imaging Applications in Complex Media

Dr. Carey M. Rappaport, Northeastern University

Overview Many important detection problems, such as finding hazardous concealed objects, can be addressed with radar. Radar is conventionally used to detect metallic objects in air or image features on relatively flat backgrounds.  However, for body-worn explosives detection, tunnel or IED detection under rough ground surfaces, or subsurface biological sensing, nearfield radar imaging can reconstruct essential features that are otherwise obscured with opaque media layers.  As long as there is a dielectric contrast between the object of interest and the surrounding background, microwaves will scatter in all directions, and multiple radar receivers can be positioned to sense this scattering. Combining the received signals coherently provides information for detection, discrimination, and characterization of hidden objects. Many of the standard antenna and radar concepts based on farfield assumptions no longer apply with nearfield imaging applications, although general concepts of spatial sampling, aperture size, and bandwidth are still important. Wave refraction and transmission at boundaries has particular importance for subsurface sensing, as does conductive power dissipation in lossy media. In whole body security scanning, the goal is to detect anomalies on the surface of the skin concealed under clothing. Skin and muscle tissue are high in water content, so millimeter waves scatter strongly. With sufficiently dense arrays of radar elements, metal object shapes can be reconstructed and dielectric objects can be characterized. There is a strong trade-off between cost (both in hardware and computation) and performance for full 3D imaging.   Spotlight Synthetic Aperture Radar (SL-SAR) concept will be discussed as a means of detecting tunnels. SL-SAR can scan large areas of terrain in a short amount of time, and with the additional formulation to consider refraction at the ground surface, Underground Focusing (UF) SL-SAR, is shown to be more accurate for focusing on targets. Tunnel detection is a difficult problem that depends on many different variables such as soil constitutive parameters and antenna configuration. In addition, this work analyzes the parametric impact of different tunnel depths, roughness topologies, and roughness heights in the UF-SL-SAR images. Radar has been used to detect and image high water content cancer tissue surrounded by fatty, low water content tissue. Specifically, array-based radar breast cancer systems have shown promise as a supplement to mammography.  In this case, the aperture is limited, since the best range of frequencies to balance penetration and resolution is 1-3 GHz, with relatively large antenna elements. Advantages and limitations of various approaches will be discussed and evaluated. Outline: Fundamentals of nearfield imaging Linear reconstruction Model-based reconstruction Multi-monostatic vs. bistatic and multistatic radar Real arrays of radar elements Planar Cylindrical Synthetic aperture arrays Refraction and transmission in the context of subsurface radar Material characteristics and their effects on wave propagation and scattering Computational methods to model wave propagation in complex media Applications Whole body imaging security scanning Ground penetrating radar for tunnel and IED detection Biomedical imaging for breast cancer detection Biography Dr. Carey M. Rappaport, Northeastern University Carey M. Rappaport received five degrees from the Massachusetts Institute of Technology:  the SB in Mathematics, the SB, SM, and EE in Electrical Engineering in June 1982, and the PhD in Electrical Engineering in June 1987.  He has been on the faculty at Northeastern University in Boston, MA since 1987, and is currently Distinguished Professor of Electrical and Computer Engineering. During fall 1995, he was 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 Organisation (CSIRO) in Epping Australia.  He has consulted for CACI, Alion Science and Technology, Inc., Geo-Centers, Inc., PPG, Inc., and as an expert witness on wireless and radar intellectual property cases.  He was Principal Investigator of an ARO-sponsored Multidisciplinary University Research Initiative on Humanitarian Demining, in which he concentrated on ground penetrating radar detection of buried threats.  He is Co-PI of the NSF-sponsored Engineering Research Center for Subsurface Sensing and Imaging Systems (CenSSIS), focusing on underground sensing of buried waste, non- invasive roadway deterioration, and illicit tunnels.  He is also Co-PI and Deputy Director of the DHS-sponsored Awareness and Localization of Explosive Related Threats (ALERT) Center of Excellence, which develops and transitions mm-wave radar sensing of concealed vehicle- and person- borne threats.  Prof. Rappaport has authored over 385 technical journal and conference papers in the areas of microwave antenna design, subsurface sensing, electromagnetic wave propagation and scattering computation, and bioelectromagnetics, and has received two reflector antenna patents, two biomedical device patents and three subsurface sensing device patents.  He is Fellow of the IEEE, and was awarded the IEEE Antenna and Propagation Society's H.A. Wheeler Award for best applications paper, as a student in 1986. 
2016 IEEE International Symposium on Phased Array Systems and Technology
18 - 21 October 2016 Waltham, MA USA
Friday,  21 October 8:00 AM - 12:00 Noon Lincoln Room

Phased Arrays for Nearfield Imaging Applications

in Complex Media

Dr. Carey M. Rappaport, Northeastern University

Overview Many important detection problems, such as finding hazardous concealed objects, can be addressed with radar. Radar is conventionally used to detect metallic objects in air or image features on relatively flat backgrounds.  However, for body-worn explosives detection, tunnel or IED detection under rough ground surfaces, or subsurface biological sensing, nearfield radar imaging can reconstruct essential features that are otherwise obscured with opaque media layers.  As long as there is a dielectric contrast between the object of interest and the surrounding background, microwaves will scatter in all directions, and multiple radar receivers can be positioned to sense this scattering. Combining the received signals coherently provides information for detection, discrimination, and characterization of hidden objects. Many of the standard antenna and radar concepts based on farfield assumptions no longer apply with nearfield imaging applications, although general concepts of spatial sampling, aperture size, and bandwidth are still important. Wave refraction and transmission at boundaries has particular importance for subsurface sensing, as does conductive power dissipation in lossy media. In whole body security scanning, the goal is to detect anomalies on the surface of the skin concealed under clothing. Skin and muscle tissue are high in water content, so millimeter waves scatter strongly. With sufficiently dense arrays of radar elements, metal object shapes can be reconstructed and dielectric objects can be characterized. There is a strong trade-off between cost (both in hardware and computation) and performance for full 3D imaging.   Spotlight Synthetic Aperture Radar (SL-SAR) concept will be discussed as a means of detecting tunnels. SL-SAR can scan large areas of terrain in a short amount of time, and with the additional formulation to consider refraction at the ground surface, Underground Focusing (UF) SL-SAR, is shown to be more accurate for focusing on targets. Tunnel detection is a difficult problem that depends on many different variables such as soil constitutive parameters and antenna configuration. In addition, this work analyzes the parametric impact of different tunnel depths, roughness topologies, and roughness heights in the UF-SL-SAR images. Radar has been used to detect and image high water content cancer tissue surrounded by fatty, low water content tissue. Specifically, array-based radar breast cancer systems have shown promise as a supplement to mammography.  In this case, the aperture is limited, since the best range of frequencies to balance penetration and resolution is 1-3 GHz, with relatively large antenna elements. Advantages and limitations of various approaches will be discussed and evaluated. Outline: Fundamentals of nearfield imaging Linear reconstruction Model-based reconstruction Multi-monostatic vs. bistatic and multistatic radar Real arrays of radar elements Planar Cylindrical Synthetic aperture arrays Refraction and transmission in the context of subsurface radar Material characteristics and their effects on wave propagation and scattering Computational methods to model wave propagation in complex media Applications Whole body imaging security scanning Ground penetrating radar for tunnel and IED detection Biomedical imaging for breast cancer detection Biography Dr. Carey M. Rappaport, Northeastern University Carey M. Rappaport received five degrees from the Massachusetts Institute of Technology:  the SB in Mathematics, the SB, SM, and EE in Electrical Engineering in June 1982, and the PhD in Electrical Engineering in June 1987.  He has been on the faculty at Northeastern University in Boston, MA since 1987, and is currently Distinguished Professor of Electrical and Computer Engineering. During fall 1995, he was 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 Organisation (CSIRO) in Epping Australia.  He has consulted for CACI, Alion Science and Technology, Inc., Geo-Centers, Inc., PPG, Inc., and as an expert witness on wireless and radar intellectual property cases.  He was Principal Investigator of an ARO-sponsored Multidisciplinary University Research Initiative on Humanitarian Demining, in which he concentrated on ground penetrating radar detection of buried threats.  He is Co-PI of the NSF-sponsored Engineering Research Center for Subsurface Sensing and Imaging Systems (CenSSIS), focusing on underground sensing of buried waste, non-invasive roadway deterioration, and illicit tunnels.  He is also Co-PI and Deputy Director of the DHS-sponsored Awareness and Localization of Explosive Related Threats (ALERT) Center of Excellence, which develops and transitions mm-wave radar sensing of concealed vehicle- and person- borne threats.  Prof. Rappaport has authored over 385 technical journal and conference papers in the areas of microwave antenna design, subsurface sensing, electromagnetic wave propagation and scattering computation, and bioelectromagnetics, and has received two reflector antenna patents, two biomedical device patents and three subsurface sensing device patents.  He is Fellow of the IEEE, and was awarded the IEEE Antenna and Propagation Society's H.A. Wheeler Award for best applications paper, as a student in 1986. 
Tutorial Session 2: Phased Arrays for Nearfield Imaging Applications in Complex Media
2016 IEEE International Symposium on Phased Array Systems  and Technology
18 - 21 October 2016 Waltham, MA USA