Overlapped feeds to increase the edge of coverage gain in multi-beam reflector antennas (original) (raw)
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Antenna arrays are very used in systems where the transmission's direction has to be decided automatically. In this project, a 16x16 square array using phase shifters capable of forming discrete beams and the beam distribution obtained according to requirements are analyzed. In addition to the beam functional analysis, the array is also analyzed by some restriction imposed by ANATEL. As a result, gain graphics are plotted for all pointing directions and the graphic of gain over the geostationary orbit is plotted along with the aforementioned restrictions.
Advanced Communication Technology Satellite (ACTS) multibeam antenna analysis and experiment
IEEE Antennas and Propagation Society International Symposium 1992 Digest, 1992
One of the most important aspects of a satellite communication system design is the accurate estimation of antenna performance degradation (Pointing error, end coverage gain, peak gain degradation, etc. are of main concern). The thermal or dynamic distortions of a reflector antenna structural system can affect the far-field antenna power distribution in at least four ways. I. The antenna gain is reduce, 2. The main lobe of the antenna can be mispointed thus shifting the destination of the delivered power away from the desired locations 3.The main lobe of the antenna pattern can be broadened thus spreading the RF power over a larger area than desired 4. The antenna pattern sidelobes can increase thus increasing the chances of interference among adjacent beams of a multiple beam antenna system or with antenna beams of other satellites. The in-house developed NASA Lewis Research Center thermal/structural/RF analysis program was designed to accurate simulate the ACTS in-orbit thermal environment and predict the RF antenna performance. The program combines well establish computer programs (TRASYS,SINDA and NASTRAN) with a dual reflector-physical optics RF analysis program. The ACTS multibeam antenna configuration is analyzed and several thermal cases are presented and compared with measurements (pre-flight).
Multi-shaped beams antennas design and technology for future communication satellites
Annales Des Télécommunications, 1989
An overview of multi-shaped beams antennas for communication satellites is presented. Microwave technologies and relevant techniques to perform beam reconfigurability are discussed by making reference to commercial satellites developed in the USA and to recent studies which Selenia Spazio completed for ESA and Intelsat. Emphasis is given to the design of advanced antenna configurations for the next generation of communication satellites with different beam and capacity reconfigurability levels. Les auteurs présentent une vue d’ensemble sur les antennes à faisceaux multiples modelés. La technologie hyperfréquence et les techniques associées sont examinées en se référant aux satellites commerciaux développés aux Etats-Unis ou aux récentes études realisées par Selenia Spazio pour I’Agence spatiale européenne et Intelsat. L’accent est mis sur les configurations d’antenne avancées destinées à la prochaine génération de satellites qui présenteront les différents niveaux de reconfigurabilité en faisceaux et en capacité.
Analysis of a generalized dual reflector antenna system using physical optics
Reflector antennas are widely used in communication satellite systems because they provide high gain at low cost. Offset-fed single paraboloids and dual reflector offset Cassegrain and Gregorian antennas with multiple focal region feeds provide a simple, blockage-free means of forming multiple, shaped and isolated beams with low sidelobes. Such antennas are applicable to communications satellite frequency reuse systems and earth stations requiring access to several satellites. While the single offset paraboloid has been the most extensively used configuration for the satellite multiple-beam antenna, the trend toward large apertures requiring minimum scanned beam degradation over the field of view 18 degrees for full earth coverage from geostationary orbit may lead to impractically long focal length and large feed arrays. Dual reflector antennas offer packaging advantages and more degrees of design freedom to improve beam scanning and cross-polarization properties. The Cassegrain and Gregorian antennas are the most commonly used dual reflector antennas. A computer program for calculating the secondary pattern and directivity of a generalized dual reflector antenna system has been developed and implemented at the NASA Lewis Research Center. The theoretical foundation for this program is based on the use of physical optics methodology for describing the induced currents on the sub-reflector and main reflector. The resulting induced currents on the main reflector are integrated to obtained the antenna far-zone electric fields. The computer program is verified with other physical optics programs and with measured antenna patterns. The comparison shows good agreement in far-field sidelobe reproduction and directivity. 17. SECURITY CLASSIFICATION
IEEE Antennas and Propagation Magazine, 2019
This paper presents some recent developments in multiple beam antennas (MBAs) based on reflectarrays for communication satellites in K-and Ka-bands. The existing high throughput satellites commonly employ four reflector antennas to provide cellular coverage formed by multiple spot beams in a four color scheme. Reflectarray antennas are proposed as an attractive solution for the design of novel MBA configurations to produce multi-spot coverage with a smaller number of apertures than conventional MBA systems based on reflector technology. Single and dual reflectarray configurations have been considered for this purpose, exploiting the reflectarrays' ability to produce independent beams in different polarizations and frequencies.
Transport and Telecommunication Journal
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Typical Array Geometries and Basic Beam Steering Methods
Any electronic system with an antenna array consists of two or more antenna elements, beam forming network, and a receiver or transmitter. Many different antenna configurations can be utilized as an antenna element in the antenna array: simple dipole, monopole, printed patch design, Yagi antenna, etc. The primary requirement for antennas mounted on/in the car is compact and aesthetic design.
Satellite ground stations with electronic beam steering
2012 IEEE First AESS European Conference on Satellite Telecommunications (ESTEL), 2012
In this work, we propose electronic beam steering via antenna arrays as a substitute for large parabolic antennas at satellite ground stations. We concentrate on two array geometries, faceted arrays and hemispherical arrays. A thorough analysis is carried out of the radiation characteristics, the array size, as well as the antenna element distribution and spacing. Moreover, in order to fulfill the requirement of the array design, that is, to achieve a higher gain at low elevation angles where the longer spacecraft to ground station distance leads to a larger range loss, we propose to adjust the number of active antenna elements, i.e., some antenna elements are turned on while others are turned off according to the required level of antenna gain. This also contributes to a concept of an optimized array design for this specific application. In the simulations, the array optimization for both array geometries is further investigated and realized with a realistic ephemeris incorporated. The numerical results support the proposal of replacing large reflector antennas by electronic beam steering via antenna arrays at satellite ground stations.