摘要 :
Eight short backfire (SBF) elements aligned on a common planar reflector form a highly efficient fan-beam array capable of yielding a maximum gain of approximately 24dB. The influence of parameter variations on the array patterns ...
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Eight short backfire (SBF) elements aligned on a common planar reflector form a highly efficient fan-beam array capable of yielding a maximum gain of approximately 24dB. The influence of parameter variations on the array patterns and directivity was experimentally determined by varying the frequency. Normalized design parameters for highest efficiency and for circular polarization capability are tabulated. All array dimensions are given in wavelengths so that each application can easily be scaled for any desired frequency. (Author)
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摘要 :
This Interim Report covers the development to date of a low-inertia commutating feed for azimuth steering the beam of a circular array. In addition to superior electrical performance over that of an electronic system, the commutat...
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This Interim Report covers the development to date of a low-inertia commutating feed for azimuth steering the beam of a circular array. In addition to superior electrical performance over that of an electronic system, the commutator offers improvements in reliability and life-cycle cost (LCC). It can be accessibly located where maintenance actions are more easily carried out than in an electronically-scanned system or a conventional rotating antenna. Non-contacting loop couplers achieve low-loss transfer and distribution of RF energy, with precise control of amplitude and phase that is needed to realize low sidelobe levels. This method of coupling is preferable to the capacitive coupling used in existing electromechanical commutating feeds, where illumination flutter results in unacceptable MTI performance. To obtain multiple beam groups in elevation, two or more commutators may be stacked on a common drive shaft.
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摘要 :
An evaluation of the design philosophies and procedures of the Cassegrain antenna is presented. An approach to the practical design of and quantitative calculations for the parameters of a Cassegrain antenna to be installed at The...
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An evaluation of the design philosophies and procedures of the Cassegrain antenna is presented. An approach to the practical design of and quantitative calculations for the parameters of a Cassegrain antenna to be installed at The Ohio State University Antenna Laboratory are described.
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摘要 :
An object is to provide for receiving a circularly polarized signal from an antenna feed (10) connected to orthogonally spaced antenna elements (11, 12, 13, 14) and for transmitting a linearly polarized signal through the same fee...
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An object is to provide for receiving a circularly polarized signal from an antenna feed (10) connected to orthogonally spaced antenna elements (11, 12, 13, 14) and for transmitting a linearly polarized signal through the same feed without switches, and without suffering a 3 dB polarization mismatch loss, using an arrangement of hybrid junctions. The arrangement is comprised of two dividing hybrid junctions (15, 16), each connected to a different pair of antenna elements and a summing hybrid junction (17). In one embodiment, a receiver (18) is connected to the summing hybrid junction directly. A diplexer (19a or 19b) is used to connect a transmitter (20a or 20b) to only one pair of antenna elements. In an alternative embodiment, designated left and right circularly polarized (LCP and RCP) transmitters (21, 22) are connected to the summing hybrid junction by separate diplexers (23, 24), and separate LCP and RCP sensitive receivers (25, 26) are connected to the diplexers in order to transmit linearly polarized signals using all four antenna elements while receiving circularly polarized signals as before. An orthomode junction (30) and horn antenna (32) may replace the two dividing hybrid junctions (15, 16) and antenna feed (10).
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摘要 :
There is a need for high gain antennas which are capable of rapid scanning and multibeam operations. The report presents a study of double-spherical Cassegrain reflector to ascertain whether this antenna is practical for these pur...
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There is a need for high gain antennas which are capable of rapid scanning and multibeam operations. The report presents a study of double-spherical Cassegrain reflector to ascertain whether this antenna is practical for these purposes. The aperture blocking,the spread of the field,and the phase and amplitude distributions are examined using geometric optical technique There is no single optimum condition,but it is shown that a proper combination of the subreflector and main reflector sizes and the position of the feed can indeed produce a promising antenna. (Author)
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摘要 :
The complete pattern of a parabolic reflector antenna was calculated using the singly-diffracted rays of the geometrical theory of diffraction, with proper corrections for the forward and real axial directions. Excellent agreement...
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The complete pattern of a parabolic reflector antenna was calculated using the singly-diffracted rays of the geometrical theory of diffraction, with proper corrections for the forward and real axial directions. Excellent agreement with experimental patterns can be expected, if the aperture blockage is not significant. The solution has the usual advantages of a solution based on the geometrical theroy of diffraction, namely, it is obtained in the form of simple functions, its computation cost is low, it is directly related to the radiation mechanism of the antenna and so it can be readily used in the design problem, and it can be easily extended and modified as the need arises. (Author)
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