Topic
Fresnel zone
About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.
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08 Jul 2016TL;DR: In this article, a real-time system for line-of-sight (LOS) survey between radio sites is presented, which includes a drone controlled by a UAV LOS System (ULS) server.
Abstract: Embodiments herein use a real-time system to conduct a line of sight (LOS) survey between radio sites. The system includes a drone controlled by a UAV LOS System (ULS) server to gather information regarding the LOS path between the radio sites. In one embodiment, the ULS server instructs the UAV to travel a LOS path between a first location and a second location, and determine a Fresnel radius at one or more defined locations along the LOS path between the first location and the second location. The ULS server determines a Fresnel zone between the first location and second location based in part on the determined Fresnel radius for each of the defined locations along the LOS path. The ULS server evaluates the Fresnel zone to determine if the LOS path can support a LOS wireless communication link.
8 citations
12 Sep 2000
TL;DR: In this paper, the authors summarized some of the growth in investigations for Fresnel zone plate lens and antennas in millimeter-wave regions, and summarized some growth in the number of applications.
Abstract: This paper summarized some of the growth in investigations for Fresnel zone plate lens and antennas in millimeter-wave regions.
8 citations
TL;DR: In this paper, a holographic approach is presented to create FZPs where the interference pattern between a spherical beam and a plane wave is recorded to obtain the FZP structure.
Abstract: Fabrication of Fresnel zone plates (FZPs) with nanometer scale resolution is one of the major challenges in lithographic fabrication. The authors present a holographic approach to create FZPs where the interference pattern between a spherical beam and a plane wave is recorded to obtain the FZP structure. The spherical beam is obtained by diffraction from a circular aperture (pinhole) in a semiopaque membrane which is illuminated by a spatially coherent extreme ultraviolet beam. The beam transmitted by the membrane serves as the reference plane wave. The resulting pattern gives rise to a FZP with outermost zone width comparable to the dimension of the circular aperture. Fabrication and test results of a FZP obtained with this method are presented. The technique offers a solution to the pattern-placement problem encountered in serial ZP writing techniques as well as high resolution potential.
8 citations
TL;DR: In this article, it is shown that when a coherent beam of light illuminates a Fresnel's double mirror, Fresnel diffraction becomes appreciable, and the authors calculate the diffracted field by applying Fresnel-Kirchhoff integral.
8 citations
TL;DR: In this article, a three-dimensional (3D) laser beam steering of focal position has been demonstrated using a single optical device, a DMD micromirror array.
Abstract: Three-dimensional (3-D) laser beam steering of focal position has been demonstrated using a single optical device—a DMD micromirror array. Laser beam focus position is controlled using dynamically adjustable zone plates. These zone plates take the form of elliptical Fresnel zone plates or other variations such as binary Gabor zone plates. Active beam pointing and control can be realized without the need for a pair of galvanometer mirrors and a focusing lens. Focusing efficiencies into an off-axis diffraction order of a few percent are typically seen and continuity between neighboring orders increases the effective field of regard. Writing multiple zone plate patterns to the DMD enables multiple focused spots to be generated and controlled independently.
8 citations