可形成聚焦波束的双反射面天线仿真设计方法

给出基于几何光学方法的可形成聚焦波束的双反射面仿真设计方法。对于给定馈源，可以通过求解一组常微分方程，得到可在所需要聚焦点形成聚焦效果的反射面面形。     

大口径反射面天线射频性能的近场聚焦测量

简要介绍了反射面天线近场聚焦测量方法,推导出了有限测试距离时用副反射面纵向偏焦补偿近场相差的计算公式,分析了近场聚焦测量与远场测量的数据结果,并给出了仿真和试验实例,仿真与试验结果吻合较好,近场聚焦法是一种可用于大口径天线性能测量的有效方法。     

一种新型双弯曲反射面天线

提出了一种新型双弯曲反射面天线,其双弯曲反射面的垂直面照射电平较低部分(此部分的中截线为抛物线)在垂直面起聚焦的效果,此部分反射面的反射波束的增益较高而满足使用要求:设计方法和计算结果一并给出,其中包括双弯曲反射面的解析表达式、垂直面照射电平从-3.39dB至-21.97dB之间的反射面在垂直面的聚焦效果.     

多波束抛物面天线设计的若干问题

本文介绍了抛物反射面的聚焦特性,指出除了主轴点状聚焦以外,尚存在偏轴非点状聚焦,还讨论了抛物反射面的多波束天线有关设计中的几个问题,最后介绍了典型的多波束抛物反射面天线。     

一种偏馈FZP天线的设计方法

本文通过对FZP反射面偏轴扫描特性进行的分析,基于菲涅尔区相位修正原理,提出一种新型的偏馈FZP反射面天线设计方法,并利用物理光学方法得到一组模拟计算的数值结果。通过与正馈FZP反射面天线的比较,证实了这种反射面天线具有一些很好的聚焦特性。有关数值结果有助于该类天线的实际设计。     

一种偏馈FZP天线的设计方法

本文通过对ＦＺＰ反射面偏轴扫描特性进行的分析,基于菲涅尔区相位修正原理,提出一种新型的偏馈ＦＺＰ反射面天线设计方法,并利用物理光学方法得到一组模拟计算的数值结果。通过与正馈ＦＺＰ反射面天线的比较,证实了这种反射面天线具有一些很好的聚焦特性。有关数值结果有助于该类天线的实际设计。     

中国天眼-“Fast“天体信号反射系统设计

本文通过分析天体位置,综合考虑反射面上相邻节点距离变幅度、促动器径向伸缩范围,建立电磁波反射面板调节的线性规划模型,并进行优化设计。首先介绍发射面板调节的工作原理,并论证调整反射面板使之成为可聚焦电磁波信号至焦点的理想抛物面的可行性。利用坐标旋转的方法,针对天体的位置调整反射面板,使接收器尽可能收到多的电磁波信号。利用促动器拉伸主索节点以调整反射面板,借助于球坐标系和坐标旋转的方法得到理想的抛物面,有效的控制整个天体信号反射系统。     

有限扫描反射面天线相控波束重构技术

该文研究一种采用聚焦馈源阵列馈电的反射面天线,相控阵馈源离开焦平面向反射面移动一定距离,位于焦散区,能够增强反射面天线的波束重构赋形能力和有限视角扫描能力。采用改进的投影矩阵法,利用仅相位控制技术,求解相控阵馈源的激励系数,有效综合了聚焦馈源偏置抛物面天线的方向图。对算例的设计达到了采用仅相位技术控制波束指向、波束赋形、旁瓣电平等性能要求,实现了相控阵馈电偏置抛物面天线的波束重构或扫描,并利用商用GRASP仿真软件验证了该文的设计结果,说明了该文方法的有效性。     

应用菲涅耳原理计算ILS下滑台保护区

仪表着陆系统下滑信标天线是通过地面反射作用形成引导飞机着陆的下滑面引导信号,反射面的反射性能直接影响下滑面的信号质量,本文通过应用菲涅耳原理对下滑信标天线反射面保护区进行了计算,可作为下滑台保护区确定的参考。     

毫米波雨雾颗粒环境传输测量系统

毫米波在颗粒环境中传输特性是毫米波通信技术的重要基础性问题。为探索毫米波传输在可控颗粒环境下的测量，基于准光学理论设计了双反射面高斯波束传输系统。该系统包含一对多张角喇叭和两个椭球聚焦反射面。多张角喇叭用于产生高斯度大于96%的高斯波束；聚焦反射面将发射波束重新聚焦，使得输出波束参数与发射波束参数相同。此外，基于矢量网络分析仪加扩频模块的实验方案，对准光传输系统在75~110 GHz频率范围进行了测试，得到该频率范围内整个系统的损耗。测试结果表明系统本身的损耗仅有2~4 dB，表现出良好的传输特性。基于本系统的初步喷水实验为可控颗粒环境下传输测量奠定了基础。     

Designing Schwarzschild dual-reflector systems

The purpose of this paper is to provide readers an easy set of equations and design parameters to generate Schwarzschild dual-reflector systems. We consider the geometry of a Schwarzschild dual-reflector system, consisting of two rotationally symmetric reflectors, which form an aplanatic system that fulfills the Abbe sine condition. This dual-reflector system ensures freedom from spherical and primary coma aberrations when the feed horn is displaced from the axis of symmetry. This is a useful property for beam-scanning or multibeam applications.     

副面修正卡塞格伦天线设计中的几个问题

本文根据几何光学理论,介绍了副面修正双反射面天线组合馈源相位中心的计算方法.并利用并矢反射系数,导出了包括差波束在内的副面散射场及天线口径分布,因而解决了副面修正天线性能参数的计算问题.     

Design of dual-reflector antennas with arbitrary phase and amplitude distributions

A synthesis method based on geometrical optics for designing a dual-reflector antenna system with an arbitrary phase and amplitude distribution in the aperture of the second reflector is presented. The first reflector may be illuminated by a pattern with an arbitrarily curved phase front. A pair of first-order ordinary nonlinear differential equations of the formdy/dx=f(x, y)are developed for the system. Questions concerning uniqueness, existence and bounds for the solutions can be answered. Calculations and numerical results for the design of a uniform amplitude and phase dual-reflector system are presented.     

A shaped offset-fed dual-reflector antenna

A shaping scheme based on geometric optics for offset-fed dual-reflector antennas is presented. A ray tube emerging from a symmetric feed horn is transformed, after reflections, into a circular beam with a uniform phase and a prescribed radial power distribution on the aperture. In this scheme, Snell's law was not imposed on the main reflector. Based on this approximate solution, computer runs were taken for a 5.5-m dish baseline system, and very satisfactory results were obtained. The system so designed not only gives very low sidelobes but also provides a very high aperture efficiency. At 12 GHz an estimated 84 percent of aperture efficiency was achieved in spite of the severe constraint that the ray intersecting the edge of the main reflector meet a -10-dBi criterion.     

Generalized classical axially symmetric dual-reflector antennas

This work presents a generalized study of classical axially symmetric dual-reflector antennas. The antenna dishes are simply described by conic sections, arranged to reduce the main-reflector radiation toward the subreflector surface. The dual-reflector configuration provides a uniform-phase field distribution over the illuminated portion of the aperture, starting from a spherical-wave feed source at the antenna primary focus. All possible configurations are characterized into a total of four distinct groups. Simple closed-form design equations and the aperture field distribution are derived, in a unified way, for all these kinds of generalized antennas using the principles of geometrical optics. The formulation is applied in a parametric study to establish the configurations yielding maximum radiation efficiency (not including diffraction effects). The design procedure is exemplified in the synthesis of a novel configuration, which is further analyzed by the moment method     

GO Shaping of Omnidirectional Dual-Reflector Antennas for a Prescribed Equi-Phase Aperture Field Distribution

A formulation is presented for shaping dual-reflector antennas designed to offer an omnidirectional coverage. The shaping procedure is based on geometrical optics (GO) principles and assumes a uniform phase distribution for the aperture field. Two distinct dual-reflector arrangements, based on the axis-displaced Cassegrain (ADC) and ellipse (ADE) configurations, are investigated. The GO shaping results are validated using the accurate analysis provided by the method-of-moments technique     

Analysis of a cluster feed for the Arecibo trireflector systemusing forward ray tracing and aperture integration

A cluster feed for the Gregorian dual-reflector feed of the Arecibo radio telescope is studied. The system is analyzed by forward ray tracing from each individual feed horn via the three reflectors to the aperture. The radiation pattern is determined by aperture integration. The analysis method is very time efficient compared with physical optics (PO) integration, the latter being unusable at high frequencies because the computer time increases by a factor proportional to the frequency to the power 4. Results obtained by the ray tracing method and PO integration are in very good agreement at frequencies low enough to be used for PO calculations. A special algorithm is developed to determine the squint and directivity of an individual main beam without computing the radiation pattern. This makes it possible to use the program very efficiently when searching for optimum cluster feed geometries. The computer programs are used to design a seven-element cluster feed for the Arecibo trireflector system     

Surface tolerance loss for dual-reflector antennas

A formula is derived to evaluate the relative influence of subreflector and main reflector surface errors on overall tolerance loss for a dual-reflector antenna. Comparisons are made with the results of random-number simulation of surface errors in a Gregorian system.     

Development of a dual-reflector feed for the Arecibo radiotelescope: an overview

The 305-m spherical-reflector antenna of the Arecibo Observatory will be equipped with a dual-reflector feed. This reflector system is often referred to as the Gregorian. An overview of the work that led to this design is given, and the basic ideas behind the design are described. The methods and algorithms that have been developed to synthesize the shapes of the two reflectors and to analyze them are reviewed. Results are given of analysis by forward ray tracing, using geometrical optics with edge-diffraction corrections included. At low frequencies, analysis is performed by physical optics (PO) integration. A `mini-Gregorian' that has been constructed, built, and tested to verify the dual-reflector feed concept is described