Fresnel zone

About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.

Alumide as a Nonmagnetic Fresnel Zone Lens at 30 GHz

Abstract: A nonmagnetic Fresnel Zone Plate Lens (FZPL) antenna with high dielectric plastic porosity controlling is proposed in this paper. Compared to conventional Fresnel plates, the proposed structure has a single homogeneous platform for transmitting mode role, making the gradient refractive index lens antenna a perfect candidate for high gain applications. A non-magnetic plastic has achieved the intended GRIN subzones homogeneously. Each desired permittivity for half-wave plate subzones is estimated with a capacitive estimation on Brakora analysis. Half-wave zone type of FZP is selected to utilize based on optic rules to realize this estimation. A Cos41-like conical horn is used as a central beam-launcher to excite the lens diaphragms and was implemented and measured at 30 GHz. The measured scattering parameters for ZP shows a better than −15 dB return loss and validate our modeling with 5 mm thickness and $3\lambda_{0}$ lateral dimension.

A Theoretical Analysis of Multiple Diffraction in Urban Environments for Wireless Local Loop Systems

Abstract: The simulation technique of Walfisch [1] is used to examine multiple diffraction in wireless local loop systems. The simulations results show that the average propagation characteristic is described by a two slope model. In the immediate vicinity of the basestation the propagation loss is found to have a distance dependence of 20 dB per decade. At greater distances the slope increases to approximately 40 dB per decade.

Estimating the field reflected from irregular terrain

Abstract: A physical-optics method of estimating the EM field reflected from terrain is proposed, that can be applied to any terrain profile, since it avoids the requirement to model any particular shape. It is expected to be of particular value when the terrain is irregular within the Fresnel zone for reflection.

Micro confocal microscopic imaging device

Abstract: The invention discloses a micro confocal microscopic imaging device, which comprises a laser, a spectroscope, a precision displacement table and a photoelectric detector, wherein a first fresnel zoneplate and a quarter-wave plate are sequentially arranged between the laser and the spectroscope; the precision displacement table is arranged below the spectroscope, a tested sample is arranged on theprecision displacement table, and a supersurface focusing unit is arranged between the spectroscope and the precision displacement table; the photoelectric detector is arranged at one side of the spectroscope; a second fresnel zone plate is arranged between the spectroscope and the photoelectric detector; and the precision displacement table is used for carrying out precision micro displacement control on the tested sample to realize two-dimensional or three-dimensional scanning imaging. Plane lenses such as the fresnel zone plates and the supersurface lens are used to carry out integrated design on the confocal microscopic imaging device, and the micro confocal microscopic imaging device with a simple and compact structure and cheaper price is formed.

Verification of Fresnel Zone Clearance for Line-of-sight Determination in 5.9 GHz Vehicle-to-Vehicle Communications

Abstract: The determination of the path clearance is one of the most important factors for channel propagation models because most of them classify their models into line-of-sight (LOS) and non-LOS (NLOS) environments. In particular, the path for vehicle-to-vehicle (V2V) communication is more easily obstructed owing to its characteristics such as low antenna heights and high mobility. In this paper, we verify the first Fresnel zone clearance, which is a widely employed method for the determination of path clearance in V2V scenarios. In the analytical model of the first Fresnel zone in V2V scenarios, the ground acts as an obstacle and thus induces NLOS environments for farther than a certain distance. In contrast, our measurement results reveal no additional loss due to the ground obstruction. Therefore, we conclude that the first Fresnel zone calculation is not applicable for determining the path clearance in V2V scenarios, which has significant impact on the accuracy of channel propagation modeling.