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[IEEE 2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) - Boston, MA, USA (2018.7.8-2018.7.13)] 2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) - Sub-Diffraction Holographic Imaging with Resonant Scatterers in Proximity of the Objects
摘要： To overcome the well-known 'diffraction limit' in the resolution of electromagnetic imaging systems, we propose the use of resonant near-field scatterers incorporated in the holographic imaging techniques. These scatterers convert a portion of the evanescent spectrum in the proximity of the object to propagating spectrum which is measurable by the antenna in the far-field.
关键词： microwave and millimeter wave imaging,sub-diffraction imaging,resonant scatterers
更新于2025-09-23 15:22:29
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Fast Modeling Methods for Estimating Imaging Performance of Whole Body Screening
摘要： Simulation of millimeter wave imaging system for whole body screening before a safety inspection manufactured is a challenging work. The conventional physical optics (PO) method is a proper high-frequency approximation method to solve the forward problem of imaging. In this letter, a modi?ed PO method is used to calculate not only metal scatterer but also non-metal dielectric medium. A ray tracing (RT) method and its modi?cation are proposed to further fast estimate the performance of multiple-input-multiple-output (MIMO) imaging system. The radiation pattern of transmitter or receiver is taken into account, then the rough imaging performance of arbitrary MIMO system on arbitrary human posture can be acquired in seconds to make the system design ?exible and convenient. The image reconstruction of the proposed method for a human body model with dielectric skin medium and metal pistol has demonstrated the applicability to real-life applications.
关键词： Millimeter wave imaging,concealed weapon detection (CWD),Image reconstruction,Physical optics (PO),Ray tracing (RT),Multiple-input-multiple-output (MIMO)
更新于2025-09-10 09:29:36
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Evaluation of Positioning Techniques for Millimeter-wave Portable Scanners
摘要： Hybrid methods that combine electromagnetic and optical three dimensional (3D) imaging can be used to scan objects or bodies at millimeter-wave frequencies by merging multiview information. The first goal of the optical model is to obtain a 3D representation of the external surface of the target under test. The second goal lies in the estimation of positions and attitude angles of the electromagnetic scanner in order to properly combine the data collected at each acquisition view. In this contribution, two different positioning techniques are evaluated. The first one is based on a conventional optical camera, whereas the second one relies on a depth camera. Finally, an example of application to security screening is used to evaluate the accuracy of both methods.
关键词： millimeter-wave imaging,RGB-D,photogrammetry,portable scanner,depth camera,structured light
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - 3D Printed Compressive Horn Antenna for High-Sensing-Capacity Millimeter-Wave Imaging
摘要： This paper presents a new millimeter-wave sensing system used for near-field imaging applications. The presented system is composed of a parabolic reflector which is fed by an array of compressive antennas. A Compressive Horn Antenna (CHA) is manufactured by inserting a dielectric piece with a pseudo-random geometric pattern inside a Pyramidal Horn Antenna (PHA). The presented CHA is capable of performing spectral coding, which is of special interest for high-sensing-capacity applications. The antenna is fabricated using additive manufacturing (3D printing) techniques and then spray coated with silver. Near-field measurements are carried out in the near-field region of the antenna. The measured fields are then compared with those of the full-wave simulations to validate the performance of the fabricated antenna. Using the surface equivalence principle, the electric and magnetic fields at the aperture of the horn antennas are used to calculate the equivalent radiating electric and magnetic currents. These currents are then integrated to an in-house physical optics-based solver to feed a parabolic reflector and image metallic scatterers in the near-field region of the system. Numerical simulations show that the imaging performance of the reflector fed by the CHAs outperforms those of the reflector fed by PHAs.
关键词： millimeter-wave imaging,3D printed antenna,compressive antenna,sensing capacity
更新于2025-09-04 15:30:14