Antenna Gain and Link Budget for Waves Carrying Orbital Angular Momentum (OAM)

This paper addresses the RF link budget of a communication system using unusual waves carrying an orbital angular momentum (OAM) in order to clearly analyse the fundamental changes for telecommunication applications. The study is based on a typical configuration using circular array antennas to transmit and receive OAM waves. For any value of the OAM mode order, an original asymptotic formulation of the link budget is proposed in which equivalent antenna gains and free-space losses appear. The formulations are then validated with the results of a commercial electromagnetic simulation software. By this way, we also show how our formula can help to design a system capable of superimposing several channels on the same bandwidth and the same polarisation, based on the orthogonality of the OAM. Additional losses due to the use of this degree of freedom are notably clearly calculated to quantify the benefit and drawback according to the case.Comment: 33 pages, 11 figure

A New Metric for Estimating the Disparity of Antenna Patterns in Synthetic Aperture Imaging Radiometry

The soil moisture and ocean salinity (SMOS) satellite has provided for about ten years systematic passive L -band measurements from space. For several months, phase 0 studies are conducted by the French space agency for a second-generation high resolution (HR) follow-on mission. This contribution is making the connection between this SMOS hr project and the SMOS mission by revisiting the following problematic: the impact of the disparity of the antenna patterns on the reconstruction floor error observed in the retrieved brightness temperatures. This impact is revisited in light of the progress made since that time and a new metric is introduced for estimating the disparity between antenna patterns. It would be helpful for the design of future missions based on imaging by aperture synthesis with interferometric arrays comprising a large number of antennas

Etudes sur la forme du plan de masse d'une antenne multibandes pour applications GPS/Galileo/Télémesure

National audienceDans la continuité d'une action de R&T du CNES menée par le LAAS et portant sur l'étude et la conception d'une antenne multibandes associant les applications GPS, Galileo et la télémesure de la plateforme générique MicroSat, une étude paramétrique a été menée sur les caractéristiques géométriques de divers plans de masse de l'antenne. Il s'agissait d'optimiser les performances radioélectriques de l'antenne en terme d'adaptation et de diagramme de rayonnement tout en minimisant si possible l'encombrement total de l'antenne. L'optimisation des performances de l'antenne a mené au choix d'un plan de masse original de forme conique

Impact of the Ground Plane Topology on the Performances of a Pyramidal Multiband Quadri-Element Antenna

International audienceThis paper presents investigations performed on the ground plane topology of a pyramidal multiband quadri-element antenna recently introduced mainly for radio navigation applications. The analyses led to a new topology of ground plane that reduces the overall height of the antenna without affecting the electrical performances of the antenna, mainly input matching and radiation patterns. A solution with flat ground plane is also investigated for applications requiring further compactness. Simulations results are presented for the different considered design assuming a frequency plan including radio navigation frequency bands (L1/L5) as well as satellite telemetry frequency band (S-band). Only the lower frequency band is considered as it is the one mostly affected by the ground plane topology

Discussion about the effect of the OAM topological charge on a microwave link budget

International audienceIn order to clearly analyze the fundamental changes when dealing with OAM waves, we try to simplify a conventional point to point microwave link. The geometrical configuration is then reduced to face to face, co-axial, annular antenna arrays. Under assumptions of uncoupled elementary sources and ideal Beam Forming Network, the global link budget is derived from an original asymptotic development and analytically exhibits the topological charge effect. A new expression for antenna's Gain is then obtained, surprisingly increasing with the topological charge l. The specific decrease previously discussed by Tamagnone with respect to the distance is found again

Que peut-on attendre des OAM? Propriétés physiques, applications aux télécommunications

National audienc

Discussion about the link budget for electromagnetic wave with orbital angular momentum

International audienceThis paper presents a discussion about the RF link budget for a communication system based on unusual waves carrying a non-zero orbital angular momentum (OAM). A typical configuration using circular antenna arrays of isotropic sources to transmit and receive OAM waves is considered. We point out issues when usual assumptions are made to express the link budget. Then, we propose to express the power budget associated with OAM in an elementary MIMO matrix approach. Using a single mode communication configuration, some basic numerical calculations and case studies based on the developed formulations can then be led and discussed, highlighting some intrinsic limitations. Indeed, the asymptotic behavior of the link budget leads to question the concepts of gain and propagation losses

Circularly Polarized EBG Antenna Using Meander Lines Polarizer as a reflector focal feed for Ka-Band Space Applications

International audienceThis article presents a first step towards the design of a multi-feed circularly polarized EBG antenna which serves as a reflector focal array. The circular polarization is obtained by using a multilayer meander lines polarizer, placed above a linearly polarized EBG antenna. The details of the antenna and the polarizer are given and the "transparent" effect of the polarizer on the antenna feed performance is emphasized after comparing the performance with and without the polarizer. The designed antenna is used to illuminate a reflector antenna for RX Ka-band space applications [29.5 - 30] GHz, and the coverage performance will be shown

Synthesis of Versatile Functionalities in Arrangements of 3D Unit-Cells

International audienceThis contribution concentrates on the conception of periodic structures that are built from metallic three-dimensional unit-cells. Such arrangements allow synthesizing diverse functionalities such as polarization conversion, frequency filtering, and impedance matching. In addition, the topologies considered here can be built monolithically employing only metal, therefore providing multiple advantages, such as low insertion losses, high power handling and manufacturing certainty