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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TL;DR: In this article, the effects of the geosynchronous thermal environment on the surface accuracy of a tetrahedral-truss support structure for a high-frequency microwave antenna concept for Earth-science monitoring have been studied.
Abstract: The effects of the geosynchronous thermal environment on the surface accuracy of a tetrahedral-truss support structure for a high-frequency microwave antenna concept for Earth-science monitoring have been studied. The thermal environment and the slow rotation of the spacecraft relative to the Sun result in long exposure to both heating and cooling conditions and, consequently, in severe temperature extremes. Resulting transient temperatures ranged from 150 to -180°C and were strongly influenced by the shadow cast by the reflector surface. The use of truss element surface coatings achieved mixed success in alleviating thermal problems. Multilayer insulation or a Sun shield worked best in reducing surface distortions, but the distortions still exceeded the required surface accuracy. Surface accuracy requirements could only be met by customization of surface coatings and element expansion characteristics.
9 citations
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09 May 1989
TL;DR: In this article, the size and apex angle of the conical reflector were optimized to yield the desired feed pattern, the optimization parameters depending on the reflector size and focal length and being obtained numerically or experimentally to maximize reflector gain.
Abstract: A dipole feed for a paraboloidal reflector antenna uses a conical reflector to direct the radiation of the dipole towards the concave reflecting surface of the parabola. The size and apex angle of the conical reflector are optimized to yield the desired feed pattern, the optimization parameters depending on the reflector size and focal length and being obtained numerically or experimentally to maximize reflector gain.
9 citations
15 Apr 1991
TL;DR: In this article, the measured radiation patterns of a 1.8 m reflector antenna were presented for three cases of a parabolic reflector partially covered by dry snow, and measurements were made at 20 GHz in one case and simultaneously at 20 and 30 GHz in two cases.
Abstract: Fading due to snow accretion on the reflector antenna is a major problem in satellite communication in Finland and other northern countries. Dry snow may stay on antennas for many days or even weeks, if the temperature is below 0 degrees C, making fading events longer. Dielectric losses of dry snow are very small and can be normally discounted, but asymmetrically gathered dry snow tilts and distorts the antenna beam due to the different phase delays of the different wave paths. Theoretically, the worst case would be a dry snow layer on the lower half of the reflector causing a phase delay of 180 degrees , when the signal entirely disappears from line of sight. The author expands research in this neglected area. The measured radiation patterns of a 1.8 m reflector antenna are presented for three cases of a parabolic reflector partially covered by dry snow. The measurements were made at 20 GHz in one case and simultaneously at 20 and 30 GHz in two cases.
9 citations
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01 Jul 2017
TL;DR: In this paper, a W-band cylindrical waveguide horn antenna with polarizer structure is designed which offers wideband left-hand circular polarization (LHCP) and symmetric radiation pattern.
Abstract: A compact W-band cylindrical waveguide horn antenna with polarizer structure is designed which offers wideband left-hand circular polarization (LHCP) and symmetric radiation pattern. It has wideband impedance matching below S 11 = −15 dB and axial ratio below 1.8 dB from 79.5 GHz to 87.5 GHz. This horn is used as a feed source for an offset parabolic reflector. The reflector antenna provides peak RHCP (right-hand circular polarization) directivity of 37.3 dBic at 86 GHz.
9 citations
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TL;DR: Defocused Gaussian beam telescope geometry and its tolerance with the changes in the values of their lenses and focalization distances are analyzed in this paper, which is very useful in systems that must operate over broad bandwidths.
Abstract: Defocused Gaussian beam telescope geometry and its tolerance with the changes in the values of their lenses and focalization distances are analyzed. The Gaussian beam telescope is very useful in systems that must operate over broad bandwidths. This device has particularly functional properties in Cassegrain radiotelescope feed systems. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 420–423, 2002.
9 citations