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Keywords = Fresnel near-field beam focusing

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12 pages, 5499 KiB  
Communication
Design of Moiré-Inspired Metasurface Lens for Focusing Electromagnetic Power in Fresnel Near-Field Region
by Tae-Heung Lim, Hyunsoo Kim, Chulhun Seo and Hosung Choo
Energies 2022, 15(11), 3911; https://doi.org/10.3390/en15113911 - 25 May 2022
Cited by 2 | Viewed by 2733
Abstract
This paper proposes a Moiré-inspired metasurface lens system to focus electromagnetic power in the Fresnel near-field region. The proposed metasurface lens (MSL) system is composed of two MSLs and a square patch antenna source. The MSLs are modeled based on the transmit phase [...] Read more.
This paper proposes a Moiré-inspired metasurface lens system to focus electromagnetic power in the Fresnel near-field region. The proposed metasurface lens (MSL) system is composed of two MSLs and a square patch antenna source. The MSLs are modeled based on the transmit phase distributions of Moiré lens theory, and each unit cell structure (patch shape and Jerusalem cross slot shape) is determined to fit the calculated transmit phase distributions at each location. When changing the unit cell structure, phase and transmittance variations are achieved over 330° and −3 dB. The square patch antenna source is then designed to excite the field to the MSLs. The measured reflection coefficients are below −10 dB at 5.8 GHz while rotating the second MSL. The focal length can be adjusted from a minimum of 38 cm to a maximum of 110 cm according to the rotation angle of the second MSL. The proposed MSL system can be employed for wireless power transmission applications to focus electromagnetic power at various locations in the near-field region. Full article
(This article belongs to the Special Issue Next Generation Wireless Charging System for Mobile Devices)
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15 pages, 1719 KiB  
Article
Efficient Holographic Focusing Metasurface
by Vinay R. Gowda, Mohammadreza F. Imani, Timothy Sleasman and David R. Smith
Electronics 2021, 10(15), 1837; https://doi.org/10.3390/electronics10151837 - 30 Jul 2021
Cited by 7 | Viewed by 3334
Abstract
We present the design and experimental demonstration of an efficient holographic metasurface aperture that focuses microwaves in the Fresnel zone. The proposed circular structure consists of two stacked plates with their periphery terminated in a conductive layer. Microwaves are injected into the bottom [...] Read more.
We present the design and experimental demonstration of an efficient holographic metasurface aperture that focuses microwaves in the Fresnel zone. The proposed circular structure consists of two stacked plates with their periphery terminated in a conductive layer. Microwaves are injected into the bottom plate, which forms the feed layer, and are coupled to the top holographic metasurface layer via an annular ring. This coupling results in an inward traveling cylindrical wave in the top layer, which serves as the reference wave for a hologram. The radiating elements consist of a slot pair with their orientations designed to couple efficiently with the cylindrical reference wave while maintaining a linearly polarized focused beam. A general condition on the slot pairs radiated power is proposed to ensure low sidelobe level (SLL) and is validated with full-wave simulation. An aperture that is 20 cm in diameter, operates at 20 GHz in the K-band frequency, and forms a diffraction-limited focal spot at a distance of 10 cm is experimentally demonstrated. The proposed near-field focusing metasurface has high antenna efficiency and can find application as a compact source for Fresnel-zone wireless power transfer and remote sensing schemes. Full article
(This article belongs to the Special Issue Wireless Power/Data Transfer, Energy Harvesting System Design, Volume II)
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9 pages, 1503 KiB  
Article
3D Conductive Polymer Printed Metasurface Antenna for Fresnel Focusing
by Okan Yurduseven, Shengrong Ye, Thomas Fromenteze, Benjamin J. Wiley and David R. Smith
Designs 2019, 3(3), 46; https://doi.org/10.3390/designs3030046 - 4 Sep 2019
Cited by 7 | Viewed by 6022
Abstract
We demonstrate a 3D printed holographic metasurface antenna for beam-focusing applications at 10 GHz within the X-band frequency regime. The metasurface antenna is printed using a dual-material 3D printer leveraging a biodegradable conductive polymer material (Electrifi) to print the conductive parts and polylactic [...] Read more.
We demonstrate a 3D printed holographic metasurface antenna for beam-focusing applications at 10 GHz within the X-band frequency regime. The metasurface antenna is printed using a dual-material 3D printer leveraging a biodegradable conductive polymer material (Electrifi) to print the conductive parts and polylactic acid (PLA) to print the dielectric substrate. The entire metasurface antenna is 3D printed at once; no additional techniques, such as metal-plating and laser etching, are required. It is demonstrated that using the 3D printed conductive polymer metasurface, high-fidelity beam focusing can be achieved within the Fresnel region of the antenna. It is also shown that the material conductivity for 3D printing has a substantial effect on the radiation characteristics of the metasurface antenna. Full article
(This article belongs to the Special Issue 3D-Printed RF Devices and Antennas)
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