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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Patent•
24 Sep 2013
TL;DR: In this paper, an antenna with a sub-reflector and a main reflector with each of them having its own focal-ring type geometry is described. But the sub-receiver is not considered in this paper.
Abstract: An exemplary embodiment of an antenna in accordance with the present invention utilizes a sub-reflector and a main reflector with each of them having its own focal- ring type geometry. The antenna cooperates with a signal transmission feed disposed at the center of the antenna axis between the first and main reflectors to emit radio signals towards the sub-reflector. The sub-reflector reflects radio waves towards a main reflector which in turn reflects the radio waves to form the beam pattern emitted by the antenna. The reflecting surface of the sub-reflector is formed by a portion of an axially-displaced ellipse rotated about the antenna axis. The reflecting surface of the main reflector is defined by a section of a parabola rotated about the antenna axis to form a reflecting surface that concavely slopes away from the antenna axis. An embodiment of the antenna provides a wide coverage conical beam with selectable beam peaks that operate over a 2.25: 1 frequency band range and provides substantially iso-flux beam density.
12 citations
Patent•
03 Apr 2002
TL;DR: A parabolic reflector lighting fixture for use as an in-the-wall or in-floor or in the ceiling light has its lamp shiftable in a lumen plane perpendicular to the axis of symmetry of the reflector through the focal point as mentioned in this paper.
Abstract: A parabolic reflector lighting fixture for use as an in-the-wall or in-the-floor or in-the-ceiling light has its lamp shiftable in a lumen plane perpendicular to the axis of symmetry of the parabolic reflector through the focal point. The parabolic reflector is limited to reflect light only between the intersection of this lumen plane and the reflector and between this intersection and the apex of the reflector.
12 citations
Patent•
08 May 1998TL;DR: In this paper, an omnidirectional microwave antenna comprises a paraboloidal reflector disposed above the ground and facing downwardly with a substantially horizontal aperture and a substantially vertical axis.
Abstract: An omnidirectional microwave antenna comprises a paraboloidal reflector disposed above the ground and facing downwardly with a substantially horizontal aperture and a substantially vertical axis. A vertically oriented feed horn is located below the paraboloidal reflector on the axis of the paraboloidal reflector and has a phase center located near the focal point of the paraboloidal reflector. A conical reflector having a shaped reflecting surface defined by the parameters of a mathematical equation extends downwardly away from the periphery of the feed horn for reflecting radiation received vertically from the paraboloidal reflector in a horizontal direction away from the conical reflector, and for reflecting horizontally received radiation vertically to the paraboloidal reflector. A radome extends downwardly from the outer periphery of the paraboloidal reflector and includes an absorber material for absorbing radiation propagated laterally from the feed horn and the conical reflector above the aperture of the feed horn.
12 citations
TL;DR: With the help of the vector theory of reflection and refraction, a novel emitting Cassegrain antenna with a semitransparent secondary mirror has been proposed and analyzed for a distant point source and according to the simulation result, this receiving antenna can nicely converge the rays from the emitting antenna.
Abstract: With the help of the vector theory of reflection and refraction, a novel emitting Cassegrain antenna with a semitransparent secondary mirror has been proposed and analyzed for a distant point source. Based on the absorptivity valued at 3.00% and the reflectivity valued at 0.10%, this new emitting antenna can increase the transmission efficiency from 63.65% to 93.85%. In addition, an off-axis parabolic receiving antenna corresponding to the emitting antenna is designed and the 3D ray-trace simulation result is given. According to the simulation result, this receiving antenna can nicely converge the rays from the emitting antenna.
12 citations
TL;DR: In this article, a rigorous procedure for calculating the antenna noise temperature is described, and applied to the antenna of the basic element for SKA training - version 1, which represents one of the SKA (square kilometer array) demonstrators.
Abstract: In this paper, a rigorous procedure for calculating the antenna noise temperature is described, and applied to the antenna of BEST-1 (basic element for SKA training - version 1), which represents one of the SKA (square kilometer array) demonstrators. The SKA will be a new-generation radio telescope, with a collecting area 50 times larger than the area of today's largest radio telescope. BEST is the Italian reduced-scale SKA demonstrator, based on the re-instrumentation of about 8000 m2 of the Northern Cross radio telescope, built with cylindrical parabolic antennas. In order to perform the antenna-temperature analysis, an electromagnetic tool to accurately evaluate the antenna pattern in the whole space surrounding the antenna itself is required. We used the commercial software GRASP8, developed by TICRA, to characterize reflector antennas. The antenna temperature was evaluated using the guideline adopted by the Antenna Task Force of the SKA world consortium. For BEST-1 at 408 MHz, we found an antenna temperature equal to 30 K in the zenith direction and 60 K at the horizon. The numerical results have been verified through several celestial calibration radio sources.
12 citations