A5042516978- Microwave Imaging and Scattering Analysis
- Millimeter-Wave Propagation and Modeling
- Metamaterials and Metasurfaces Applications
- Indoor and Outdoor Localization Technologies
- Antenna Design and Analysis
- Advanced SAR Imaging Techniques
- Electromagnetic Scattering and Analysis
- Antenna Design and Optimization
- Innovative Educational Techniques
- Soil Moisture and Remote Sensing
- Face recognition and analysis
- Electromagnetic Compatibility and Measurements
- Geophysical Methods and Applications
- Telecommunications and Broadcasting Technologies
Duke University
2015-2022
Plasmonics (United States)
2016-2019
MetaMateria (United States)
2017
Abstract We demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements spatially-diverse field patterns, diffraction-limited images human-sized subjects are reconstructed. The is driven by single microwave source swept over band frequencies (17.5–26.5 GHz) and switched between collection transmit receive metasurface panels. High fidelity image reconstruction requires precise model for...
Recently, a frequency-diverse, metamaterial-based aperture has been introduced in the context of microwave and millimeter wave imaging. The generic form is that parallel plate waveguide, which complementary metamaterial elements patterned into upper couple energy from waveguide mode to scene. To reliably predict imaging performance such an prior fabrication experiments, it necessary have accurate forward model predicts radiation aperture, for scattering arbitrary target scene, set image...
We present the design, fabrication, and experimental characterization of a 2-D, dynamically tuned, metasurface aperture, emphasizing its potential performance in computational imaging applications. The dynamic aperture (DMA) consists an irregular, planar cavity that feeds multitude tunable metamaterial elements, all fabricated compact, multilayer printed circuit board process. design considerations for element as radiator, associated biasing circuitry, well parameters are examined discussed....
Emerging metasurface antenna technology enables flexible and low cost massive multiple-input multiple-output (MIMO) millimeter-wave (mmW) imaging for applications such as personnel screening, weapon detection, reconnaissance, remote sensing. This work proposes an orthogonal coded active illumination (OCAI) approach which utilizes simultaneous, mutually transmit signals to illuminate the scene being imaged. It is shown that OCAI robust code amplitude phase imbalance introduced by imperfect...
We demonstrate a technique for calibrating frequency-diverse, multistatic, computational imaging system. A frequency-diverse aperture enables an image to be reconstructed primarily from set of scattered field measurements taken over band frequencies, avoiding mechanical scanning and active components. Since systems crucially rely on the accuracy forward model that relates measured transmitted fields, deviations actual system will rapidly degrade performance. Here, we study performance at...
We review the evolution of metasurface antennas for computational microwave imaging and highlight advantages disadvantages various configurations. As an illustrative example, we examine a system comprising dynamic printed cavities as modular building blocks. These can generate multitude spatially diverse, voltage-controlled illumination patterns, therefore encode scene's reflectivity distribution into set measurements that be postprocessed to produce image. single-port devices act...
Computational imaging at microwave frequencies has gained traction due to its potential for obtaining high-quality images with fast acquisition rates. Complex and diverse radiation patterns form the cornerstone of this approach. Electrically large antennas, such as mode-mixing cavities metamaterial apertures, have proven be effective platforms generating waveforms. Due complex nature these near field scanning is often required characterize their patterns. However, accurate knowledge produced...
We present a study of computational through-wall imaging using dynamically reconfigurable metasurface antenna (DMA). The DMA consists single-feed, electrically-large microstrip line, loaded with individually addressable metamaterial radiators. Each resonator is integrated diode, enabling it to be switched on (radiating) or off (non-radiating) by an externally applied voltage. By switching subsets the array elements off, spatially diverse radiation patterns are formed that scattered wall and...
Computational imaging is a proven strategy for obtaining high-quality images with fast acquisition rates and simpler hardware. Metasurfaces provide exquisite control over electromagnetic fields, enabling the radiated field to be molded into unique patterns. The fusion of these two concepts can bring about revolutionary advances in design systems security screening. In context computational imaging, each pattern serves as single measurement scene; scene then interpreted estimating...
This paper summarizes the recent advances in using frequency-diverse metasurfaces for computational imaging microwave and millimeter wave regimes. Frequency-diverse apertures are defined as structures that can generate distinct radiation patterns a function of frequency. Such waveforms multiplex scene information into set backscattered measurements, which be decoded algorithms. In this manner, these retrieve scene's reflectivity map fast frequency sweep (all-electronic operation),...
We present a ray-tracing analysis of smart motion detector based on dynamically reconfigurable metasurface antenna (DMA). A DMA consists an array metamaterial radiators excited by single-port waveguide or cavity. By incorporating simple switchable components into each element and addressing them individually, DMAs can generate myriad spatially distinct radiation patterns alter as function applied voltage. These have the potential to probe all regions room set rooms detect motion, even when...
We present the design, fabrication, and experimental characterization of a two-dimensional, dynamically tuned, metasurface aperture, emphasizing its potential performance in computational imaging applications. The dynamic aperture (DMA) consists an irregular, planar cavity that feeds multitude tunable metamaterial elements, all fabricated compact, multilayer printed circuit board process. design considerations for element as radiator, associated biasing circuitry, well parameters are...
Advances in non-mechanical frequency-diverse apertures and reconstruction algorithms have made real-time millimeter-wave data acquisition volumetric imaging possible. Fast frame rates allow people motion, which represents a tremendous opportunity to increase security screening throughput over existing solutions where subjects must individually strike hold pose. However for systems specularity coupled with limited viewing perspectives diminish coverage individual images. To mitigate these...