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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17 Nov 2003
TL;DR: In this article, the importance of the concept of penumbra width in radio propagation studies is stressed, and it is shown that the breakpoint between interference and diffraction zones corresponds to the well-known criterion of a path clearance equal to 0.6 of the first Fresnel zone radius.
Abstract: The importance of the concept of penumbra width in radio propagation studies is stressed in this paper. The propagation over a smooth spherical earth is the mathematical model used for discussing the transition from light to shadow or, in other words, between interference and diffraction zones. The breakpoint between these two zones corresponds to the well-known criterion of a path clearance equal to 0.6 of the first Fresnel zone radius. It is shown here that this criterion can be related to the relative position of the penumbra width associated to each terminal.
20 Oct 2014
TL;DR: In this article, the dipole wave scattering from flat square plates is detailed with numerical examples and the accuracy of the fields predicted by this new fringe wave expressions is confirmed by comparing with MoM.
Abstract: Fringe wave current components of modified edge representation (MER) equivalent edge currents (EECs) are modified by Fresnel zone number. The dipole wave scattering from flat square plates are detailed with numerical examples and the accuracy of the fields predicted by this new fringe wave expressions is confirmed by comparing with MoM.
01 Jul 2018
TL;DR: This paper presents a technique to reduce the specular reflection effect from the ground surface to an L-band dual-polarized Single Antenna Polarimetric Active Radar Calibrator (SAPARC) with high and stable RCS (55 dBsm) by the means of using a dihedral centered at the Speular point.
Abstract: This paper presents a technique to reduce the specular reflection effect from the ground surface to an L-band dual-polarized Single Antenna Polarimetric Active Radar Calibrator (SAPARC) with high and stable RCS (55 dBsm) by the means of using a dihedral centered at the specular point. The SAPARC uses a single antenna and a precision Ortho-Mode Transducer (OMT) to isolate between transmit and receive paths. The system is designed to achieve a 30 dB signal-to-clutter ratio while operating in free space. Degradation of such high signal-to-clutter ratio happens due to the side lobe absorption of the specular reflection from the ground. To reduce the effect of such strong reflection, it is proposed to use a dihedral positioned at the specular point on the ground covering the Fresnel zone of the SAPARC antenna. The received field is reduced by an average of 25 dB over most of angular range of interest.
TL;DR: Young's interference experiment was used to analyze the statistical properties of a certain class of spatially partially coherent, cyclostationary, optical fields as mentioned in this paper, which is a class of optical fields that we consider in this paper.
Abstract: Young's interference experiment is used to analyze the statistical properties of a certain class of spatially partially coherent, cyclostationary, optical fields.
Patent•
03 Jul 2013
TL;DR: In this article, the structure of a 3D optical body comprising Fresnel prisms is described, and the structure is arranged in a slope sequence that defines one or more saddle points.
Abstract: An optical film or other optical body has a structured surface comprising Fresnel prisms. The Fresnel prisms define a complex topography. For example, a first and second Fresnel prism may have elongated first and second plan view shapes that form a “wye” (Y-shaped) feature. Alternatively or in addition, the Fresnel prisms may be arranged such that slopes of the Fresnel prisms define one or more saddle points. Furthermore, one or more of the Fresnel prisms may have prism shapes in plan view that include undulating portions, and the Fresnel prisms may be arranged in a slope sequence that defines one or more inflection points. The Fresnel prisms may be refractive or reflective, and they may provide the structured surface with a 3-dimensional appearance.