Topic
Reflective array antenna
About: Reflective array antenna is a research topic. Over the lifetime, 4366 publications have been published within this topic receiving 57884 citations.
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TL;DR: In this paper, a simple point source analysis is used to prove that completely decorrelated reception can be achieved from two linear antennas with an arbitrarily small spacing, and the conditions necessary to achieve this are consistent with two high gain (superdirective) beams in opposite directions.
Abstract: A simple point source analysis is used to prove that, in theory, completely decorrelated reception can be achieved from two linear antennas with an arbitrarily small spacing. The conditions necessary to achieve this are consistent with two high gain (superdirective) beams in opposite directions. It is shown that the horizontal radiation patterns and correlation coefficient of arrays of vertically orientated linear antennas can be found via an exact relation to simple, point-source theory that includes the effects of mutual coupling. This theory leads to practically achievable optimum diversity designs at closer spacings than previously thought possible. The theory is illustrated for a dual antenna configuration and can be extended to multiple antennas.
38 citations
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14 May 1990TL;DR: In this paper, the lengths of the lower-frequency helices are adjusted to move the nulls in their radiation patterns into congruence with the unwanted peaks of the array pattern, thereby suppressing the grating lobes.
Abstract: Arrays of helical antennas are desired for operation at spaced-apart frequencies, such as 1.5 and 2.5 GHz. In order to reduce mutual coupling between the antenna elements of the lower-frequency array, they are spaced apart by more than λ. Grating lobes occur due to the spacing. The lengths of the lower-frequency helices are adjusted to move the nulls in their radiation patterns into congruence with the unwanted peaks of the array pattern, thereby suppressing the grating lobes. In order to reduce the total area of the combined arrays, the higher-frequency antennas of the second array are interleaved with the elements of the first array. At the higher frequency, the antenna elements of the second array are spaced apart even further, in terms of wavelength, than the elements of the first array, so mutual coupling of the antennas of the second array is reduced even more than in the first array. The number of turns of the helices of the second array are adjusted to bring nulls of the individual radiation patterns into coincidence with the unwanted grating lobes.
38 citations
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TL;DR: In this article, the authors proposed using 4, 5, or even 6 faces to scan the hemisphere, and showed that the performance of the 6-face array can be improved significantly.
Abstract: Phased-array antennas utilizing fixed, planar apertures and designed to provide electronic-beam scanning throughout a hemisphere require a minimum of 3 apertures or faces. Each face covers one-third of the hemisphere and scans to an angle 63\deg from broadside. This causes a ratio of broadside beamwidth to maximum-scan beamwidth of 0.45. Also, assuming no power reflected from the aperture broadside scan, a large amount of power would be reflected at maximum scan because of mutual coupling. These two effects cause a variation in realized gain of 4.1 db. By using 4, 5, or even 6 faces to scan the hemisphere, the antenna performance may be considerably improved. Each face of the 6-face array scans to an angle of only 41\deg from broadside, and exhibits a beamwidth ratio of only 0.76. The power reflected from the aperture is greatly reduced, and the variation in realized gain is only 1.3 dB. The relative number of elements required by the various designs depends on the particular basis of comparison. Equalizing poorest performance by specifying equal realized gains at the respective maximum scan angles requires about 18 percent more elements for 3 faces than for 6 faces. Three of the four chosen bases for comparison yielded fewest elements for the 4-face array.
37 citations
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01 Jun 1984TL;DR: In this paper, a quasistatic energy approach is proposed to define the equivalent radius of thin cylindrical antennas in the presence of arbitrarily cylindrically shaped dielectric and/or magnetic materials.
Abstract: The concept of equivalent radius of electrically thin cylindrical antennas is well known in the case of metallic antennas in homogeneous dielectric media. It is possible, however, to define equivalent radius also in cases of thin cylindrical antennas in the presence of arbitrarily cylindrically shaped dielectric and/or magnetic materials. The approach is essentially a quasistatic energy approach. It enables a large number of complicated problems of such antennas to be reduced to the equivalent problem of a cylindrical antenna of circular cross-section with an appropriate single-type dielectric or (preferably) magnetic cover, which can be solved with ease. Illustrative examples, including those of strip antennas on a dielectric substrate, indicate high accuracy of the results obtained by the proposed theory.
37 citations
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22 Jun 2003TL;DR: In this paper, a linearly polarized microstrip array in Ku-band is achieved by having proper impedance matching throughout the array and by properly using the corporate and series fed by microstrip transmission lines.
Abstract: Excellent efficiency of a linearly polarized microstrip array in Ku-band is achieved by having proper impedance matching throughout the array and by properly using the corporate and series fed by microstrip transmission lines. The cavity-backed microstrip patch is used to obtain relatively wide bandwidth. The auto-tracking Ku-band antenna in the azimuth direction has developed with a very low profile for vehicle's rooftop mounting, as well as, a low manufacturing cost. The main beam of array is tilted 15/spl deg/ away from the broadside direction to provide optimum coverage for Korea satellite III.
37 citations