雷达天线风荷的应力应变分析

天线被广泛应用于通信、雷达导航等领域，天线结构的静力学、动力学特性对天线整体的电/机性能有着极其重要的影响。且抛物面天线的口面面积较大，工作环境较为恶劣，因此风荷载成为影响天线正常运转的最主要荷载。文中用有限元法对雷达天线装置在风荷作用下产生的应力应变，进行了详细的分析介绍，并给出了分析的云纹图，以达到为天线处于优化状态下工作提供科学的分析结论和设计依据。     

一种新型抛物面天线设计

抛物面天线是一种普遍使用的雷达跟踪天线。因其跟踪精度高而要求其波束很窄，造成搜索发现目标困难。本文提出一种将圆口径抛物面天线改进成为一种集搜索、跟踪于一体的新型天线，既便于搜索发现空中目标，又不影响跟踪精度。     

大型面天线的瞬态风荷分析

在ANSYS环境中,首先建立了某35m口径抛物面天线的有限元模型;然后详细介绍了天线在脉动风荷作用下的动力学分析方法;最后计算分析了天线处于指平姿态下,在自重和平均风速为20m/s的脉动风载下的变形,并给出了分析结果;验证了基于ANSYS二次开发、MATLAB编程结合有限元法的分析方法的实用性。     

7m天线的数字化建模及静、动态分析

在ANSYS环境中,首先建立了某7m口径圆抛物面天线的数字化模型;然后在自重和风荷的作用下,对天线进行了静力学分析,验证了天线的设计刚度和强度;最后计算分析了天线的前20阶固有频率和振型,为改进和优化设计提供了依据。     

主被动复合导引头天线共口径配置研究

对主被动复合制导系统中的几种共口径天线配置技术进行了研究,其中被动测向系统中的天线为一个或多个宽带螺旋天线,主动雷达中的天线为标准旋转对称抛物面天线或其切割变形结构.对主被动天线之间的相互作用和影响进行了分析计算,并以此为依据进行性能比较和方案选优.     

抛物面反射天线的空域瞬态极化特性研究

以天线的空域指向为变化因素来分析研究抛物面天线的空域极化特性,采用表面电流法计算了天线远场的主极化和交叉分量,进而利用空域极化比分布,瞬态极化投影集等空域瞬态极化描述子研究了雷达坐标系下不同方位角和俯仰角下典型抛面天线极化特性的变化规律.通过计算和分析比较,结果表明,在空域指向的不同位置,抛物面天线的极化特性服从一定规律变化,这对抛物面天线空域极化特性的应用提供了理论依据和支持.     

浅谈卫星广播电视系统的接收天线

分析了前馈式抛物面天线和后馈式抛物面天线主要部件（如反射面、馈源喇叭、极化变换器、圆矩匹配器等）的工作原理，并讨论了天线的主要指标：增益、旁瓣特性、噪声温度和极化轴比。     

星载合成孔径成像雷达发展现状与趋势

回顾了星载合成孔径成像雷达的发展历史,总结了现有星载合成孔径成像雷达的技术特点.现役星载合成孔径雷达的主要工作模式有聚束、条带和扫描3种,雷达采用的天线形式分为相控阵天线和抛物面天线2大类,而且性能要求全面的系统主要采用相控阵天线.最后指出了星载合成孔径雷达今后可能的发展方向,认为更高的空间分辨率、高分辨率下的宽幅成像与干涉成像是今后技术发展的主要方面.     

圆抛物面二维平面风载荷和三维空间风载荷的关系

本文利用圆抛物面二维平面风载荷系数推导出三维空间的任意仰角、风向角下的风载荷系数。该关系式具有通用性，对实体抛物面天线、网状天线、漏孔天线、带罩天线均可应用，文后还给出了一些二维平面风载载体系数的图表资料，以供选择使用。     

屋顶微波铁塔的地震效应与安装设计

一、屋顶微波铁塔结构的特点 随着通信事业的迅速发展,在全国正在建设星罗棋布的微波通信网。作为市内终端站而使用的屋顶微波铁塔,已经大批地耸立起来。 以往的微波通信市内终端站建筑多数采用自立式铁塔或钢筋混凝土塔。在城市建设中,高层建筑不断涌现,因此,对微波通信用抛物面天线要求的挂高越来越大,相应的微波通信塔所承受的风荷载及地震作用也随之而增大。由于微波通信对天线方向性有严格的要求,天线支承结构的变形受到重视。如果继续采用自立式铁塔或钢筋混凝土塔,势必要增加建设投     

舰载雷达天线载荷的确定

以三种舰载警戒雷达天线为例，对天线的风载荷、惯性载荷和自重作了分析，提出了减小天线系统风载荷的主要途径     

某雷达方位电机功率的计算

因客观条件的限制，有些雷达天线不能用风洞试验的方法得出其风阻力系数和风力矩系数，通过与具有相似天线口径和结构形式并做过风洞试验的雷达天线做类比，得出了某雷达天线的风阻力系数和风力矩系数，并据此对其方位电机驱动功率进行了计算。     

天线罩对抛物面单脉冲天线极化特性的影响机理和仿真分析

单脉冲定向技术是目前最准确的电子定向技术之一, 被广泛应用于微波毫米波跟踪、监视、通信、测量、天文观测等系统.为了保护雷达天线免受环境的影响, 许多单脉冲天线都采用天线罩, 这会对单脉冲天线方向图的极化结构产生影响, 另外, 有意的电子欺骗干扰如交叉极化干扰会对定向性能产生较大影响.文章以雷达导引头普遍采用的X波段抛物反射面幅度比较单脉冲天线为对象, 分析了抛物面结构、初级馈源特性、天线罩引起交叉极化分量的机理, 建立了典型物理参数下的计算模型, 在Ludwig第三定义下对加入天线罩前后单脉冲天线交叉极化特性进行仿真, 综合考虑了天线几何形状、偏置结构、天线扫描等因素对极化特性的影响.结果表明:多种因素会引起单脉冲天线显著的去极化效应, 复杂的方向图极化结构使得单脉冲雷达导引头的定向精度敏感于电波极化方式, 这为进一步开展交叉极化对抗单脉冲跟踪技术研究提供了重要理论基础.     

On airborne measurement of the sea surface wind vector by a scatterometer (altimeter) with a nadir-looking wide-beam antenna

A pilot needs operational information about wind over sea as well as wave height to provide safety for a hydroplane landing on water. Near-surface wind speed and direction can be obtained with an airborne microwave scatterometer, a radar designed for measuring the scatter characteristics of a surface. Mostly narrow-beam antennas are applied for such wind measurement. Unfortunately, a microwave narrow-beam antenna has considerable size that hampers its placement on flying apparatus. In this connection, a possibility to apply a conventional airborne radar altimeter as a scatterometer with a nadir-looking wide-beam antenna in conjunction with Doppler filtering for recovering the wind vector over sea is discussed, and measuring algorithms of sea surface wind speed and direction are proposed. The obtained result can be interesting for many studies in oceanography, meteorology, air-sea interaction, and climate change and for creation of an airborne radar system for amphibious airplane safe landing on the sea surface, in particular for search and rescue operations in coastal areas.     

First-order correction of aberrations in Cassegrainian and Gregorian antennas

Cassegrainian and Gregorian reflector arrangements are needed for multibeam ground station and satellite antennas. In these antennas one or more feeds are displaced from the focus. This displacement normally causes aberrations, due primarily to astigmatism and coma. In a previous article, astigmatism was eliminated for small feed displacements by centering the antenna aperture with respect to the equivalent paraboloid axis. In this article coma is also removed by deforming the reflectors without causing spherical aberration, and simple expressions for the deformation coefficients are derived. The analysis applies in general to an arrangement ofNreflectors. The deformations required to correct astigmatism, if the antenna aperture is not centered is also derived.     

The polarization losses of offset paraboloid antennas

In this paper the electric field in the aperture of offset front-fed paraboloid antennas and open Cassegrainian antennas, excited by an electric dipole or Huygens source in the focus, is compared with the fields of front-fed circularly symmetrical paraboloid reflector antennas and classical Cassegrainian antennas. The aperture field forms the basis of expressions to calculate the polarization efficiency of all four types of antenna. Computed results are given, showing that offset antennas can compete with front-fed paraboloids if they are excited by an electric dipole; the classical Cassegrainian antenna, however, shows better results. If offset antennas are excited by a Huygens source, the result is very unfavorable compared with the symmetrical antennas which show no cross polarization.     

Application of rectangular and elliptical dielcore feed horns toelliptical reflector antennas

The pattern characteristics of elliptical reflector antennas are investigated when they are fed by rectangular and elliptical horns partially filled with a dielectric. The bandwidth characteristics of these dielcore horns are superior to those of their corrugated horn counterparts. Representative reflector patterns are computed to properly demonstrate the utility of these feeds for reflector antennas with elliptical apertures. This reflector antenna exhibits high efficiency and low cross polarization, and may be suitable for radar and satellite antenna applications. The antenna configuration may become useful in relatively small antennas where more than 10% cross-polar bandwidth is required. The efficient dielcore horns may also be used as feeds for elliptical nonshaped dual-reflector antennas     

Synthesis of offset dual shaped subreflector antennas for control of Cassegrain aperture distributions

Many existing large ground reflector antennas have been designed as Cassegrain systems-i.e., paraboloid/hyperboloid combinations. Other large ground antennas are simply paraboloid designs. Upgrading the gain of these systems to a gain comparable to that obtainable with a dual shaped reflector antenna system has been an important and costly objective of many such ground stations. A potentially economic method for such an antenna upgrade is presented herein. It involves a redesign of only the subreflector portion of a Cassegrain antenna or the introduction of a subreflector feed system for a parabaloid. A pair of offset subreflectors are synthesized which will give a controllable high gain amplitude distribution in the aperture of the large paraboloid. The synthesis method that is used is based on an approximate formulation for an offset dual shaped high gain antenna that was first presented by Galindo-Israel and Mittra in 1977. In that approximate formulation, the geometrical optics (GO) energy was scattered from a subreflector and then from a second large reflector which reflected a uniform phase distribution. In the present offset dual shaped subreflector (DSS) antenna, the second reflection is from a smaller (sub) reflector and it scatters a spherical wave that feeds a hyperboloid or feeds a large paraboloid directly. Excellent results are shown for the approximate synthesis of the DSS.     

等离子体天线原理与设计

等离子体天线因具有隐身、动态重构、超宽带等优点,可广泛应用于多功能雷达、电子对抗等军事技术领域。等离子体天线主要包括等离子体柱形电介质天线和反射面天线2种形式。基于表面波在等离子体中的传播特性,给出了柱形等离子体天线系统设计;基于等离子体反射电磁波特性,给出了反射面等离子体天线系统设计,为等离子体天线技术趋于实用化提供了必要的理论及技术准备。