Showing papers on "Cassegrain antenna published in 1969"
TL;DR: In this paper, an analysis theory of the shape-beam doubly curved reflector antenna is described, which utilizes a computer solution approach to achieve an accurate knowledge of the principal and cross-polarization elevation and azimuth patterns by numerically integrating the field contributions over the entire reflector surface.
Abstract: An analysis theory of the shaped-beam doubly curved reflector antenna is described. The analysis computes the far-field patterns by calculating the current density distribution on the nonanalytic surface that the shaped-beam doubly curved reflector presents using the physical optics vector approximation. The presented theory utilizes a computer solution approach to achieve an accurate knowledge of the principal and cross-polarization elevation and azimuth patterns by numerically integrating the field contributions over the entire reflector surface. A comparison of the computed and measured principal plane patterns is shown.
21 citations
15 Jan 1969
TL;DR: Calibration program for 16 ft diam parabolic antenna of radio telescope at millimeter wave observatory was described in this paper, where the radio telescope was equipped with a millimeter-wave observatory.
Abstract: Calibration program for 16 ft diam parabolic antenna of radio telescope at millimeter wave observatory
17 citations
TL;DR: In this article, the authors describe a package antenna specially designed for mounting on a slender tapered aluminum mast and gives typical measured electrical characteristics, which is used in a 1.5-mile experimental repeater installation operating at 11 GHz.
Abstract: This paper describes a packaged antenna specially designed for mounting on a slender tapered aluminum mast and gives typical measured electrical characteristics. The antenna is used in a 1.5-mile experimental repeater installation operating at 11 GHz. The masts and foundations for the experimental system are described briefly. The antenna package is an upright cylinder, a shape chosen to minimize mast twisting caused by wind, and to present a pleasing appearance in combination with a slender mast. The radiating elements consist of a waveguide aperture feed, a 30-inch parabolic reflector mounted with its axis vertical at the top of the package, and a 45-degree flat reflecting plate similar to an inverted periscope. The space below the 45-degree reflector houses all the repeater electronics. Because of the shielding effect of the cylindrical housing, this antenna like the horn-reflector antenna, has very low radiation in the far side and back lobe regions.
13 citations
Patent•
12 Mar 1969
TL;DR: In this paper, the main lobe of an antenna with a large spherical reflector and a small reflector may be oriented with respect to the large reflector by virtue of the displacement of the small reflectors.
Abstract: An antenna having a large spherical reflector and a small reflector, wherein the main lobe may be oriented with respect to the large spherical reflector by virtue of the displacement of the small reflector, these displacements being rotations around the center of curvature of the large reflector, and the waves irradiating the small reflector being spherical around the same center, the beam formed by these waves shifting with the displacement of the small reflector.
9 citations
TL;DR: In this article, an additional subreflector is introduced between the Gregorian corrector and the spherical reflector, in order to cause the power of the feed horn to be uniformly distributed over the main reflector aperture.
Abstract: A technique is proposed for raising the efficiency of sphereical-reflector antennas embodying the Gregorian method of phase correction. The method is based on the Galindo-Williams modified Cassegrain antenna. An additional subreflector is introduced between the Gregorian corrector and the spherical reflector, in order to cause the power rom the feed horn to be uniformly distributed over the main reflector aperture. Equations are presented which enable the co-ordinates of the subreflectors to be computed. Two examples are given and a theoretical effieciency of 93% is predicted in one case.
8 citations
Patent•
05 Sep 1969
TL;DR: In this article, a microwave antenna assembly which includes a second reflector in the form of an asymmetrical portion of a paraboloid and a main reflector, which forms a generally flat planar surface, is described.
Abstract: A microwave antenna assembly which includes a second reflector in the form of an asymmetrical portion of a paraboloid and a main reflector in the form of a generally flat planar surface which forms an acute angle with the second reflector. A radiating or receiving device is located at the focal point of the paraboloid spaced from but in proximity to the end of the main reflector remote from the second reflector.
6 citations
TL;DR: In this paper, a system is described which achieves wide-angle beam scanning from a parabolic reflector antenna by movement of an adaptive primary-feed system about a defined locus, which performs a sampled spatial Fourier transformation of the focal plane field in order to obtain a uniform power distribution prior to phase compensation and summation.
Abstract: A system is described which achieves wide-angle beam scanning from a parabolic reflector antenna by movement of an adaptive primary-feed system about a defined locus. The feed system performs a sampled spatial Fourier transformation of the focal-plane field in order to obtain a uniform power distribution prior to phase compensation and summation. Scanning of ±15 beamwidths with less than 0.5dB loss in gain and negligible beam distortion has been demonstrated experimentally.
5 citations
TL;DR: In this article, the antenna system described is one of the experiments on NASAs ATS-III spin stabilized satellite that was launched on November 5, 1967 and has been operating satisfactorily since.
Abstract: The antenna system described is one of the experiments on NASAs ATS-III spin stabilized satellite that was launched on November 5, 1967. It was put into synchronous orbit shortly thereafter and has been operating satisfactorily since. Using a line source feed illuminating a parabolic cylindrical reflector, a linearly polarized gain over 17 dB is achieved. The antenna is positioned by means of a vernier type stepping motor-drive system that points the antenna beam towards earth within approximately \pm0.7 degree in accordance with instructions received on the satellite from the ground control station. Prior to launch, the antenna system was subjected to extensive qualification testing. Confidence in a desired five-year life in orbit for the motor-drive system was obtained by testing the lubrication system and bearings for 7800 hours at temperatures ranging from -80\deg F to +120\deg F at vacuum pressures as low as 1 \times 10^{-8} torr.
2 citations
01 Jan 1969
1 citations
01 Jan 1969
01 Jun 1969
TL;DR: In this article, the authors examined the geometrical limitations on the use of an endfire-line source as a feed for a Cassegrain aerial and found no more stringent restrictions than those imposed by the system itself.
Abstract: As a feed for a paraboloid, an endfire-line source facilitates polarisation diversity while having beamshaping potential for high efficiency. The geometrical limitations on the use of an endfire-line source as a feed for a Cassegrain aerial are examined and found to be no more stringent than those on the use of the Cassegrain system itself. In a Cassegrain aerial, the hyperboloid is usually in the near field of the feed. The focusing of a line feed to remove the resulting phase error is discussed. The aperture blocking by a line feed is also discussed, and is found to be less than half that of a horn feed, giving easier vertex matching.