Topic
Cassegrain antenna
About: Cassegrain antenna is a research topic. Over the lifetime, 3207 publications have been published within this topic receiving 28278 citations.
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01 May 2006
TL;DR: Results of Kaband test results indicate that improved antenna surface shape accuracy (sub-millimeter values) is required for efficient operation, and shape optimization, tooling technology, fabrication processes, and active shape control techniques are being developed to enable Kaband operations.
Abstract: The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) and SRS Technologies (SRS) are collaborating on research and development of lightweight thin-film adaptive antennas. On-axis, off-set, and Cassegrain antennas, from 0.3m to 4m in aperture, are currently being designed, fabricated, and radio frequency (RF) characterized via range testing. The designs address requirements for space based systems as well as inflatable terrestrial radome antennas. Fixed, deployable, and adaptive test structures are being developed to support the antennas during testing and future operations. RF characterizations of off-set and on-axis antennas have been performed in the NASA GRC Far Field and Near Field facilities at frequencies from X-band to Ka-band. Thus far, frequencies through Ku-band have indicated excellent antenna performance. Kaband test results indicate that improved antenna surface shape accuracy (sub-millimeter values) is required for efficient operation. Thus, shape optimization, tooling technology, fabrication processes, and active shape control techniques are being developed to enable Kaband operations. SRS has developed and demonstrated thin film antenna shape control via a 5m aperture electro-statically controlled thin film. Recently, SRS and NASA collaborated with Georgia Tech to validate an adaptive beam forming algorithm that could enable a network of lower cost thin film antenna system clusters to replace the large costly antenna systems currently in use. In 2006, SRS and NASA will assemble and RF characterize a 2.4m thin film Cassegrain antenna system that could enable the use of large aperture satellitebased antennas with feed components that are integrated with the satellite bus. All of this successful lightweight thin-film adaptive antenna research and development has the potential to enhance current RF communications capabilities and enable many future RF requirements that need efficiently packaged deployable antennas with large apertures.
18 citations
Patent•
30 Jun 1983
TL;DR: In this article, a front collimating paraboloid reflector was used as the back reflector to increase the frequency range of the scanning antenna. But the back reflecting layer was not considered.
Abstract: A polarizer reflector includes a reflecting layer backing a meander-line polarizer effective to convert the incident beam from linear polarization to circular polarization during the propagation of the beam forwardly through the polarizer, and to reconvert the beam reflected from the reflecting layer from circular polarization to linear polarization but rotated at a predetermined angle, preferably at a right angle, with respect to the polarization of the incident beam. Also described is a reflecting plate-type scanning antenna including a front collimating paraboloid reflector with the above-described polarizer reflector serving as the back reflector, which arrangement has been found to substantially increase the frequency range of the scanning antenna.
18 citations
TL;DR: In this article, a simple geometric derivation of the equation for designing an offset dual reflector antenna with perfect rotational symmetry and zero cross polarization is given, which is the same as the one presented in this paper.
Abstract: A simple geometric derivation is given of the equation for designing an offset dual reflector antenna with perfect rotational symmetry and zero cross polarization.
18 citations
Patent•
15 Feb 1972
TL;DR: In this article, an optimized reflector antenna is provided which includes a reflector with a rim of adjustable width around its perimeter and a feed system having a predetermined spacing from the reflector.
Abstract: An optimized reflector antenna is provided which includes a reflector with a rim of adjustable width around its perimeter and a feed system having a predetermined spacing from the reflector. The rim is excited by radiation coupling and its edge acts like a secondary radiator that yields a substantial and unique effect on the radiation patterns of the antenna by preselecting the rim dimensions in amplitude and phase in reference to the feed system.
18 citations
01 Jan 2003
TL;DR: The Inmarsat 4 Spacecraft user link or mobile antenna system consists of a 9m deployable reflector and a feed array with 120 helical elements as discussed by the authors, where over 220 simultaneous RF beams are created by applying vector weights to the feed elements under the control of the onboard digital signal processor.
Abstract: The Inmarsat 4 Spacecraft user link or mobile antenna system consists of a 9m deployable reflector and a feed array with 120 helical elements. Over 220 simultaneous RF beams are created by applying vector weights to the feed elements under the control of the onboard digital signal processor (DSP). The simultaneous transmission and reception requires the achievement of very low levels of passive intermodulation (PIM). The mission requires continuous coverage over fixed ground cells for orbital inclinations of up to 3°. This is achieved by uploading modified beam weights on a daily basis. This requires a large number of beam weights to be presynthesized. In addition to the communication beams, a system of RF sensing beams are deployed in order to enhance the spacecraft pointing capability and hence overall communication performance.
18 citations