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, a tri-mode conjugate matched feed was proposed to suppress the unwanted high cross-polarization and beam squinting in an offset parabolic reflector antenna.
Abstract: The design and development of a tri-mode conjugate matched feed, to suppress the unwanted high cross-polarisation and beam squinting in an offset parabolic reflector antenna, are presented. In a smooth-walled cylindrical waveguide, TE 11 , TM 11 and TE 21 modes are combined in proper amplitude and phase to configure a tri-mode conjugate matched feed. The performance of the proposed tri-mode horn was evaluated, and its simulated far-field radiation pattern is found to be in close agreement with the measured radiation pattern. This horn was then used as a primary feed device to illuminate the linearly polarised offset parabolic reflector antenna, and significant reduction in the cross-polarisation has been achieved in the secondary radiation pattern. Similarly, by illuminating the offset reflector with a circularly polarised matched feed, a squint-free radiation pattern has been achieved.
11 citations
01 Jun 1988
TL;DR: In this article, the feasibility of electromagnetic compensation for reflector antenna surface distortions is investigated, and a simulation study is carried out to examine the antenna performance as a function of feed array size and number of elements.
Abstract: The feasibility of electromagnetic compensation for reflector antenna surface distortions is investigated. The performance characteristics of large satellite communication reflector antenna systems degrade as the reflector surface distorts, mainly due to thermal effects from solar radiation. The technique developed can be used to maintain the antenna boresight directivity and sidelobe level independent of thermal effects on the reflector surface. With the advent of monolithic microwave integrated circuits (MMIC), a greater flexibility in array fed reflector antenna systems can be achieved. MMIC arrays provide independent control of amplitude and phase for each of the many radiating elements in the feed array. By assuming a known surface distortion profile, a simulation study is carried out to examine the antenna performance as a function of feed array size and number of elements. Results indicate that the compensation technique can effectively control boresight directivity and sidelobe level under peak surface distortion in the order of tenth of a wavelength.
11 citations
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TL;DR: The evolution of the largest antenna of the US NASA Deep Space Network (DSN) is described in this paper, beginning with its initial 64m operation at S-band (2295 MHz) in 1966 and continuing through the present Ka-band operation at 70 m. Although their diameters and mountings differ, these parabolic antennas all employ a Cassegrainian feed system, and each antenna dish surface is constructed of precision-shaped perforated-aluminum panels that are secured to an open steel framework.
Abstract: The evolution of the largest antenna of the US NASA Deep Space Network (DSN) is described. The design, performance analysis, and measurement techniques, beginning with its initial 64-m operation at S-band (2295 MHz) in 1966 and continuing through the present Ka-band (32-GHz) operation at 70 m, is described. Although their diameters and mountings differ, these parabolic antennas all employ a Cassegrainian feed system, and each antenna dish surface is constructed of precision-shaped perforated-aluminum panels that are secured to an open steel framework. >
11 citations
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TL;DR: In this paper, the authors extended the analysis to the case where the primary feed illumination is not symmetric, because real primary feeds usually have unequal E - and H -plane beamwidths.
Abstract: Gored umbrella parabolic reflectors with symmetric aperture illumination have been treated analytically in a recent paper. This communication extends the analysis to the case where the primary feed illumination is not symmetric, because real primary feeds usually have unequal E - and H -plane beamwidths. The gore loss and the shift in the defocusing curve obtained using the modified gain expression are in excellent agreement with values measured for a smooth parabolic reflector and a gore parabolic reflector of the same diameter.
11 citations
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TL;DR: In this article, the deformations of a reflector antenna surface from the radiated far-field amplitude pattern were analyzed using a vectorial approach, which exploits a new factorization of the aperture-field distribution and takes into account both the available information concerning the undistorted antenna and the measurement accuracy.
Abstract: This paper presents a new method for the diagnosis of the deformations of a reflector antenna surface from the radiated far-field amplitude pattern. The method is fully vectorial and allows for working with a shaped beam antenna. The approach exploits a new factorization of the aperture-field distribution and takes into account both the available information concerning the undistorted antenna and the measurement accuracy. Particular care is devoted to the analysis of the well-posedness of the problem and to the avoidance of stagnation points which can trap the algorithm away from the true solution. The effectiveness of the method and its superior performance with respect to the commonly used successive projections algorithms are demonstrated by a numerical analysis. >
11 citations