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首页> 外文期刊>Radio Science >Cylindrical and conical shrouds for the reduction of ground noise of paraboloidal antennas
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Cylindrical and conical shrouds for the reduction of ground noise of paraboloidal antennas

机译：圆柱和圆锥形护罩，用于降低抛物面天线的地面噪声

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摘要

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 feed-support struts.
机译：可以通过安装从反射器边缘向前延伸的护罩来减少反射器天线的外溢噪声。护罩可防止地面辐射进入饲料。使用矩量法分析了直径为40波长的对称抛物面天线，配有圆柱形和圆锥形护罩。平行于反射器轴的圆柱形罩可以降低天线噪声，但会显着提高前半球的旁瓣电平，并且还会降低天线增益。这些缺点可以通过使用向外张开的锥形护罩来克服。这样的罩减少了后半球中的溢出瓣，从而降低了天线噪声温度，但是在前半球中产生了圆锥形的旁瓣。可以通过使用两个不同喇叭角的圆锥体构建护罩或弯曲其横截面来降低此旁瓣的峰值水平。使用几何光学，可以预测噪声温度的下降以及前半球圆锥形旁瓣的位置和水平，以达到有用的精度。罩的增加增加了主光束附近的交叉极化水平。但是，如果将护罩与反射器边缘相连的尖角替换为平滑过渡，则会降低这种效果。然后，交叉极化的水平处于与从进料-支撑杆散射产生的水平相当的水平。

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  • 来源
    《Radio Science》 |1997年第6期|2139-2148|共10页
  • 作者

    T. L. Landecker; R. J. Smegal; J. M. McKinley;

  • 作者单位

    Dominion Radio Astrophysical Observatory, National Research Council, Penticton, British Columbia, Canada;

    Dominion Radio Astrophysical Observatory, National Research Council, Penticton, British Columbia, Canada Electrical Engineering Department, University of Alberta, Edmonton, Alberta, Canada;

    Dominion Radio Astrophysical Observatory, National Research Council, Penticton, British Columbia, Canada Electrical Engineering Department, University of Alberta, Edmonton, Alberta, Canada;

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  • 正文语种 eng
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  • 关键词

    Reflector antennas; Method of moments; Antenna radiation patterns; Gain; Microwave antennas; Feeds;

    机译：反射天线;矩量法;天线辐射方向图;增益;微波天线;馈电;

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