A GTD analysis of shroud-surrounded reflector antenna

Hwang, Y.; Han, C. C.

doi:10.1109/aps.1978.1147900

Cited by 2 publications

(3 citation statements)

References 3 publications

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“…A prime fed reflector antenna surrounded by conductive shroud is an effective and low cost configuration to suppress the far-out sidelobes and the backlobe. Because of this conductive shroud, the aperture field is changed and the electric field at the edge of the shroud is rapidly-varying [4]. The aim of this study is determining the optimum shroud length providing maximum gain, minimum sidelobe and backlobe levels.…”

Section: Shroud Effectmentioning

confidence: 99%

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Analyzing of the feed line and the shroud effects on a reflector antenna performance

Gurcan

Basaran

Turetken

2011

2011 XXXth URSI General Assembly and Scientific Symposium

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High gain, low sidelobe and backlobe levels are important parameters in the reflector antenna design. These parameters are being vital important for the antennas used in radar systems, especially in military applications. If the design of the reflector is made without considering the implemantation stage, the characteristics mentioned above can not be provided. To manage this performance reduction, some improvements should be added to the design in the theoretical design stage. This paper propose two analysis for increasing the performance of a prime fed reflector antenna. The first analysis is choosing the true feedline mechanism and the second one is the effect of shroud usage. These analysis are made for an X-band waveguide fed prime focus reflector antenna. Numerical results and chosen design configuration are also presented in the numerical results section.

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Section: Shroud Effectmentioning

confidence: 99%

“…It has been mentioned as absorber-lined tunnels in [1] and analysed with GTD in [3] and [4]. In addition the diffraction effects and the pattern calculations with and without shroud are shown in [3].…”

Section: Introductionmentioning

confidence: 99%

Analyzing of the feed line and the shroud effects on a reflector antenna performance

Gurcan

Basaran

Turetken

2011

2011 XXXth URSI General Assembly and Scientific Symposium

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“…However, a search of the literature reveals very few papers in which such shrouds are discussed. In addition to Koch and Hollmann [1967] cited above, Hwang and Han [1978] and Narasimhan et al [1983] have analyzed the effects of shrouds on the radiation patterns of reflector antennas. The latter authors calculate the effect of a very long cylindrical shroud and compare measured and calculated radiation patterns.…”

Section: Introductionmentioning

confidence: 99%

Cylindrical and conical shrouds for the reduction of ground noise of paraboloidal antennas

Landecker¹,

Smegal²,

McKinley³

1997

Radio Science

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Abstract. The spillover noise of a reflector antenna can be reduced by attaching a shroud extending forward from the edge of the reflector; the shroud prevents ground radiation from entering the feed. Symmetrical paraboloidal antennas of diameter 40 wavelengths, equipped with cylindrical and conical shrouds, are analyzed using the method of moments. A cylindrical shroud, parallel to the reflector axis, may reduce antenna noise, but it raises the sidelobe level in the front hemisphere substantially and can also reduce antenna gain. These drawbacks can be overcome by using a conical shroud, flared outward. Such a shroud reduces the spillover lobes in the back hemisphere, thus lowering the antenna noise temperature, but generates a conical sidelobe in the front hemisphere. The peak level of this sidelobe can be reduced by building the shroud using two cones of different flare angles or by curving its cross section. The decrease in noise temperature, as well as the location and level of the conical sidelobes in the front hemisphere, can be predicted to useful accuracy using geometrical optics. The addition of a shroud increases the level of cross polarization near the main beam. However, this effect is reduced if the sharp corner where the shroud joins the reflector rim is replaced by a smooth transition. The level of cross polarization is then at a level comparable to that produced by scattering from feedsupport struts. IntroductionThermal radiation from the ground is one of the principal sources of noise in microwave systems using reflector antennas. Receiver noise can be reduced to 10 K or less using modern receiver technology, and ground noise can easily become the dominant contributor to system noise. In this paper we investigate the use of a cylindrical or conical shroud or fence, attached at the reflector rim, to reduce ground noise in paraboloidal antennas. The antennas we consider are symmetrical reflectors, fed at the prime focus, but our methods are applicable to many types of reflector antennas, and we reach quite general conclusions.The antennas which we discuss are paraboloids of diameter 8. MHz. This paper is the third in a series concerning the noise performance of these antennas at 1420 MHz. In the first paper, Anderson et al. [1991] analyzed the various contributions to the total antenna noise and showed that the most significant sources of noise are ground radiation reaching the feed directly over the edge of the reflector (spillover) and ground radiation scattered from the feed-support struts into the aperture; these two contributions are approximately equal. In the second paper, Landecker et al. [1991] analyzed scattering of ground radiation from the feed-support struts and showed how this source of noise could be reduced. In this paper we study methods for reducing spillover noise.Our study began experimentally. A cylindrical shroud of length I = 0.91 m was attached to the rim of one of the 8.53-m antennas, parallel to the antenna axis. Antenna temperature at 1420 MHz was reduced substantial...

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A GTD analysis of shroud-surrounded reflector antenna

Cited by 2 publications

References 3 publications

Analyzing of the feed line and the shroud effects on a reflector antenna performance

Analyzing of the feed line and the shroud effects on a reflector antenna performance

Cylindrical and conical shrouds for the reduction of ground noise of paraboloidal antennas

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