Review of Metasurface Antennas for Computational Microwave Imaging

Imani, Mohammadreza F.; Gollub, Jonah N.; Yurduseven, Okan; Diebold, Aaron V.; Boyarsky, Michael; Fromentèze, Thomas; Pulido-Mancera, Laura; Sleasman, Timothy; Smith, David R.

doi:10.1109/tap.2020.2968795

Cited by 143 publications

(97 citation statements)

References 130 publications

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“…Let assume that the distance between dipoles is deeply sub-wavelength so in the near field region only Fourier components with |k ρ | >> k are considered, then the calculations can be significantly simplified. Under this condition, the approximation −jk z ∼ = |k ρ | can be made [35]. By substituting (6b) in (2), the magnetic field can be found in the position of the receiver magnetic dipole as eq.…”

Section: Huygens' Metasurface For Near-field Wptmentioning

confidence: 99%

“…Metasurface can be defined as a two-dimensional counterpart of metamaterial state that exhibits attractive electromagnetic responses that are not found in natural materials. It has various applications in various fields, such as perfect electromagnetic absorption [33], conformal transformation optics [34], metasurface antennas [35], nonlinear diatomic metasurface [36], reflection-less zero refractive index [37], creating electromagnetic illusions [38], and mantle cloaking [39]. Recently, much research has been done on increasing the WPT efficiency utilizing metasurface.…”

Section: Introductionmentioning

confidence: 99%

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Optimal Huygens’ Metasurface for Wireless Power Transfer Efficiency Improvement

Younesiraad¹,

Bemani²,

Matekovits³

2020

IEEE Access

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In this paper, we investigate the electromagnetic response of a Huygens' metasurface (HMS) embedded between the transmitter and receiver coils of a near field wireless power transfer (WPT) system and their interactions for the feasibility of increasing efficiency. To analyze the proposed configuration, we use the point-dipole approximation to describe the electromagnetic fields and boundary conditions governing HMS to calculate the mutual inductance between the coils and to obtain closed-form analytical expressions. The proposed theory shows that by optimally designing the HMS inclusions, the amplitude of the mutual inductance between the transmitter and receiver coils in the near-field WPT can be increased, resulting in improved efficiency. Finally, by drawing on the proposed theory, we design a thin layer and finite-size HMS consisting of 64 elements. The bianisotropic Omega-type particle is used to design the HMS to improve the efficiency of the sample WPT system at the frequency of 100 MHz. The results of the full-wave simulation show that the power transfer efficiency in the free space increases from 25% to 42% in the presence of the proposed HMS. INDEX TERMS Wireless power transfer, Huygens metasurfaces, power transfer efficiency.

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Section: Huygens' Metasurface For Near-field Wptmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimal Huygens’ Metasurface for Wireless Power Transfer Efficiency Improvement

Younesiraad¹,

Bemani²,

Matekovits³

2020

IEEE Access

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“…The designs require control of the radiating aperture by high-intensity photonics aligned with the millimeter-wave optical axis. Standoff imaging at centimeter waves with quasirandom illumination on the target through metasurface antennas has also been reported [6]. There, the region of interest is illuminated in a complex way through resonant structures that each contribute a mode to the illumination.…”

Section: Introductionmentioning

confidence: 97%

Holograms with neural-network backend for submillimeter-wave beamforming applications

Tamminen

Palli

Ala‐Laurinaho

et al. 2020

Passive and Active Millimeter-Wave Imaging XXIII

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We present a new method to carry out localization based on distributed beamforming and neural networks. A highly dispersive hologram, is used together with a terahertz spectrometer to localize a corner-cube reflector placed in the region of interest. The transmission-type dielectric hologram transforms input pulse from the spectrometer into a complex pattern. The hologram causes complicated propagation paths which introduce delay so that different parts of the region of interest are interrogated in a unique way. We have simulated the emitted pulses propagating through the hologram. The hybrid simulation combines the finite-difference and physical optics methods in time domain and allows for evaluating the dispersion and directive properties of the hologram. The dispersive structure is manufactured of Rexolite and it has details resulting in varying delay from 1 to 19 wavelengths across the considered bandwidth. The spectrometer is configured in reflection mode with wavelets passing in to the region of interest through the hologram. A data-collecting campaign with a corner-cube reflector is carried out. The effective bandwidth for the localization is from 0.1 THz to 2.1 THz, and the measured loss is 57 dB at minimum. The collected data is used to train a fully-connected deep neural network with the known corner-cube positions as labels. Our first experimental results show that it is possible to predict the position of a reflective target in the region of interest. The accuracy of the prediction is 0.5-0.8 mm at a distance of 0.17 m.

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“…Another such example is a coded aperture, in which the transmitted and received wavefronts probing the imaged scene and collecting the back-scattered information are passed through a set of masks with spatio-temporally varying transparency values [29][30][31][32]. Such a modulation can be realized using semiconductor based elements, such as PIN diodes and varactors, to load the radiating elements across the coded aperture and tune their radiation characteristics to create spatio-temporally varying masks [31][32][33]. This spatio-temporal mapping aperture concept can be thought of as a large aperture antenna that can radiate complex, quasi-random radiation patterns or measurement modes.…”

Section: Introductionmentioning

confidence: 99%

Hardware Enabled Acceleration of Near-Field Coded Aperture Radar Physical Model for Millimetre-Wave Computational Imaging

Sharma¹,

Yurduseven²,

Deka³

et al. 2021

PIER B

Self Cite

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There is an increasing demand in real-time imagery applications such as rapid response to disaster rescue and security screening to name a few. The throughput of a radar imaging system is mainly controlled by two parameters; data acquisition time and signal processing time. To minimize the data acquisition time, various methods are being tried and tested by researchers worldwide. Among them is the computational imaging (CI) technique, which relies on using coded apertures to encode the radar back-scattered measurements onto a set of spatio-temporally incoherent radiation patterns. Such a CI-based imaging approach eliminates the requirement for a raster scan and can substantially simplify the physical hardware architecture. Equally important is the processing time needed to retrieve the scene information from the coded back-scattered measurements. In CI, the simplification in the hardware layer comes at the cost of increased complexity in the signal processing layer due to the indirect mapping and compression of the scene information through the spatio-temporally incoherent transfer function of the coded apertures. To address this particular challenge, this paper presents a hardware-based solution for CI signal processing using a Field Programmable Gate Array (an Xilinx Virtex-7 (XC7VX485T) FPGA chip) architecture. In particular, the proposed method consists of calculating the CI sensing matrix using the FPGA chip and storing it on the FPGA platform for image reconstruction. For the adjoint operation, the calculated sensing matrix is applied on the measured back-scattered waves from the target object. We demonstrate that the FPGA based calculation can reach 21.9 times faster speed than conventional brute-force solutions.

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Review of Metasurface Antennas for Computational Microwave Imaging

Cited by 143 publications

References 130 publications

Optimal Huygens’ Metasurface for Wireless Power Transfer Efficiency Improvement

Optimal Huygens’ Metasurface for Wireless Power Transfer Efficiency Improvement

Holograms with neural-network backend for submillimeter-wave beamforming applications

Hardware Enabled Acceleration of Near-Field Coded Aperture Radar Physical Model for Millimetre-Wave Computational Imaging

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