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分析了非赋形双偏置天线产生椭圆波束的机理,将馈源的椭圆波束照射到轮廓线为椭圆形的付反射面上,通过双偏置天线的对称转换原理,主反射面产生椭圆波束.馈源波束由矩形口径的多模喇叭产生,它提供了等化的方向图.给出了馈源及天线的方向图计算公式.实验结果表明,实测方向图基本与理论计算一致.与其他类型的椭圆波束天线相比,本天线加工简单,同时天线效率也较高. 相似文献
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本文采用偏置馈源口径场技术从理论上分析了偏置波束场型和增益,研究和计算了慧形象差影响所引起的增益损失。研制出的双波束馈源系统,可用于任意前馈卫星站的改造;3m双波束卫星接收天线增益高、副瓣低、噪声小。 相似文献
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<正> Ⅰ.引言偏置抛物面反射器的主要优缺点偏置抛物面反射器不论址在结构上,还是在分析上都很复杂,其主要优点是:(1)降低了口径遮挡影响,如图1所示;(2)能把反射器对初级馈源的反作用减至最小。其缺点是:当被线极化初级馈源照射时,偏置反射器在天线辐射场内产生交叉极化分量;当使用园极化时,虽不产生交叉极化分量,但使天线波束偏离电轴。对于小的偏置反射器,在线极化情况下,也能观测到这种偏置影响。 相似文献
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赋形波束双弯曲反射器天线理论研究 总被引:7,自引:0,他引:7
本文综述了赋形波束双弯曲反射器天线理论之研究。主要内容是:反射器的分类问题;提出了可采用一般的椭圆型条带(称为斜条带)来组成反射器,而水平带和焦点带只是它的特殊情形,使得综合理论更一般化;给出了此类天线远区场的主极化分量和交叉极化分量的计算公式,以及馈源斜置时和馈源偏离轴线时天线的远区场计算公式,尤其是还推导了在主辐射区内天线远区场的渐近公式。 相似文献
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本文研究分析了以赋形介质透镜和赋形副镜作为组合馈源的环焦反射镜天线,导出天线各部件的几何轮廓计算公式,提出了设计方法,导出了主镜反射场、孔径场和天线各种极化分量辐射场计算公式.本文还导出了以射线单位矢表示微波光学中的反射定律、折射定律、反射系数和折射系数的公式.这些公式适用于分析计算各种由透镜和反射镜组合而成的天线系统. 相似文献
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本文综述了欧洲卫星多波束的天线发展的新技术,对各种多波束反射面天线或陈列天线的反射面、馈源、波束成形网络、辐射贴片等的新理论、新技术、新应用作了述评。 相似文献
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A mathematical model of the circularly polarized feed is developed in this paper. The approach for the Jacobi-Bessel series
expansion of the physical optics radiation integral studied by R. Mittra et al. is extended to the case of circular polarizition.
A computation method for the circularly polarized contoured beam of the offset reflector antennas is analysed. Representative
numerical result is given for effective isotropic radiated power contour-plot of the western zone coverage of Chinese territory
by the 7-element array illumination. 相似文献
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A Novel Beam Squint Compensation Technique for Circularly Polarized Conic-Section Reflector Antennas
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Depolarization properties of offset reflector antennas 总被引:2,自引:0,他引:2
The cross polarized radiation for linearly polarized excitation and the beam displacement for circularly polarized excitation have been investigated for offset reflector antennas. Numerical calculations are given to illustrate the dependence upon the angletheta_{0} between the feed axis and the reflector axis as well as upon the half-angletheta_{c} subtended at the focus by the reflector. In the casetheta_{0} = theta_{c} = 45deg , measured results have been obtained for both linearly and circularly polarized excitations with a dual mode feed illuminating an offset paraboloid. The cross polarized radiation of horn reflector and open Cassegrainian antennas rises sharply to rather high values off the beam axis; however, in general, the maximum cross polarized radiation of offset reflector antennas can be made small by using a small angle between the feed and reflector axes. The cross polarization caused by offset is compared with that caused by an unbalanced feed pattern. The effect of the longitudinal current distribution and of departure of the surface from a paraboloid on cross polarization are also examined. The clarification of these cross polarization properties is found to be valuable in the design of reflector antennas. 相似文献
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The design of a linearly polarised contoured beam reflector antenna for a European coverage requirement is described. The antenna is a 1.1 m offset reflector, fed by an array of only five rectangular feed horns, operating in a 10.7?11.7 GHz band. The minimum gain requirement of 28 dBi for the contoured beam, in contrast to the current ECS-1 CEPT (Conference Europeenne de Poste et Telecommunication) elliptical Eurobeam gain requirement of 25 dBi, is achieved. 相似文献
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The development and application of a numerical technique for the rapid calculation of the far-field radiation patterns of a reflector antenna from either a measured or computed feed pattern are reported. The reflector is defined by the intersection of a cone with any surface of revolution or an offset sector of any surface of revolution. The feed is assumed to be linearly polarized and can have an arbitrary location. Both the copolarized and the cross polarized reflector radiation patterns are computed. Calculations using the technique compare closely with measured radiation patterns of a waveguide-fed offset parabolic reflector. The unique features of this technique are the freedom from restrictive feed assumptions and the numerical methods used in preparing the aperture plane electric field data for integration. 相似文献
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为了使星载通信天线产生1个赋形波束覆盖服务区,同时产生1个固定点波束和1个有限扫描点波束,该文提出一种由2个赋形反射面和3个馈源组成的混合反射面天线。该天线是以赋形主反射面共用为基础,等效为2副单馈源单偏置反射面天线和1副双偏置格里高利型赋形反射面天线,分别产生赋形波束、固定点波束和有限扫描点波束。通过对一副口径为1.2 m的天线各个波束进行仿真实验,赋形波束在Ku收、发频段时波束覆盖区边缘(EoC)方向性系数为27.5 dBi,固定点波束在C收、发频段时天线口径效率高于70%,通过将赋形副反射面及对应馈源横向偏焦实现Ka收、发频段的点波束在服务区内外的扫描。仿真结果表明,该混合反射面天线可实现C/Ku/Ka频段的同时通信任务。 相似文献
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Fiebig D. Wohlleben R. Prata A. Rusch W.V.T. 《Antennas and Propagation, IEEE Transactions on》1991,39(6):774-779
Numerical calculations have been carried out and the beam squint for circular polarized excitation has been measured using a 100 m telescope. The telescope was operated in the Gregorian mode, where the equivalent focal length equals 387.5 m. The feed horn was laterally displaced by 1.364 m from the optical axis at the system focus. Good agreement was obtained between the numerical calculations and the experimental results. The authors found a shift of the two radiation patterns of ≃2 arcsec. The orientation of the beam squint in the configuration with a laterally displaced feed is different from the orientation in offset reflector antennas 相似文献
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Lateral-feed displacement in a paraboloid 总被引:9,自引:0,他引:9
The beam shift and degradation of a paraboloidal reflector with an offset feed is analyzed by the scalar plane wave theory. Higher order coma terms are included with the feed at its optimum axial position. The beam characteristics for a tapered circularly symmetric illumination are presented. The range of validity of the approximate analysis is indicated. 相似文献
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For the design of the satellite antenna for the future geostationary (GEO) satellite communication or DBS (direct broadcasting satellite) applications to serve the Taiwan Island region, it may be required to have a antenna beam which effectively covers the Taiwan region and reduces the antenna radiation level in the nearby area of mainland China. Two cases of the Ka-band (20 GHz) satellite antenna, a shaped offset reflector antenna to synthesize a contoured beam and an elliptical offset reflector antenna to generate an elliptical beam, have been studied. This paper presents the comparison and discussion of the antenna coverage performance of the two designs 相似文献
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A beam squint has been found to occur in the field radiated by an offset paraboloid antenna illuminated by a feed with linear polarisation in the plane of offset. The squint, whose existence has been confirmed by computed and measured radiation patterns, occurs in the offset plane, and is typically 0.03 of a beamwidth for a reflector of 6-wavelengths diameter. An assessment is given of the likely effect of the squint on the performance of an offset reflector radiating a circularly polarised field 相似文献