Optimization of the Physical Aperture of the Parabolic Reflector Antenna

In fields like astronomy and radar technology, high-gain antennas are required for long-distance communication. Due to its relatively large gain, the use of parabolic antennas has become very popular over time, because they can easily achieve gains of above 30 dB at microwave and higher frequencies. Today, most systems’ success depends on how well the antennas perform. These antennas are available in different types and sizes. Each antenna’s effective area usually has less than the actual physical area of the antenna surface. This means that the unused area of the antenna is massive, and a waste. The aim of the research is to show that the actual physical aperture of a parabolic antenna can be reduced as much as possible to equal the effective area, as given by the antenna formula, thereby saving manufacturing costs, improve the aesthetics. In other words, the focus of this work is to experimentally show that reflector antenna can be made of smaller sizes but better performance. Measurements were taken from different positions from a parabolic antenna, the signal level measured and compared with signal levels for optimal performance.

Study on Clutter Model and Characteristics of Airborne Radar with Parabolic Conformal Phased Array

The studies on clutter modeling and suppression of airborne radar with a parabolic conformal array are uncommon due to the complexity of this type of antenna array configuration.The correct understanding of clutter characteristics for airborne radar with a parabolic conformal antenna array is the prerequisite and foundation of optimal suppression of this type of clutter.This paper establishes the model of clutter echo of airborne parabolic conformal phased array radar and analyzes the structure characteristics and the distribution features of this type of clutter.The simulation results show that this type of clutter has the following characteristics：1） The main lobe on the azimuth is seriously broadened,2） the power spectrum presents strong heterogeneity,and 3） the freedom degrees are high.Based on the existing related clutter suppression methods,we verified the correctness of the constructed clutter model.This work has an important guidance to further study on clutter suppression methods in airborne parabolic conformal array radar.

Review of Large Spacecraft Deployable Membrane Antenna Structures

The demand for large antennas in future space missions has increasingly stimulated the development of deployable membrane antenna structures owing to their light weight and small stowage volume. However, there is little literature providing a comprehensive review and comparison of different membrane antenna structures. Space-borne membrane antenna structures are mainly classified as either parabolic or planar membrane antenna structures. For parabolic membrane antenna structures, there are five deploying and forming methods, including inflation, inflation-rigidization, elastic ribs driven, Shape Memory Polymer （SMP）-inflation, and electrostatic form- ing. The development and detailed comparison of these five methods are presented. Then, properties of membrane materials （including polyester film and polyimide film） for parabolic membrane antennas are compared. Additionally, for planar membrane antenna structures, frame shapes have changed from circular to rectangular, and different ten- sioning systems have emerged successively, including single Miura-Natori, double, and multi-layer tensioning systems. Recent advances in structural configurations, tensioning system design, and dynamic analysis for planar membrane antenna structures are investigated. Finally, future trends for large space membrane antenna structures are pointed out and technical problems are proposed, including design and analysis of membrane structures,materials and processes, membrane packing, surface accuracy stability, and test and verification technology. Through a review of large deployable membrane antenna structures, guidance for space membrane-antenna research and applications is provided.

Thermal deformation analysis of the composite material satellite antenna

Controlling the thermal deformation is a crucial index for the design of the satellite antenna. To calculate and measure the satellite antenna’s thermal deformation is also an important step for the design of satellite antenna. Based on the foundation of equivalent assumption, the thermal deformation of the parabolic satellite antenna was analyzed by the finite element method for different design project. The best design project that had the minimum of the thermal deformation could be obtained through changing the lay-angle, lay-layers and lay-thickness of each layer. Results show the asymmetry structure has the minimum of thermal deformation. This paper may provide useful information for the further investigation on the coupling of thermal-stress structure.

Analysis and Design of a New Shaped Spherical Reflector Antenna with a Horn Feed

A design method of a new shaped spherical reflector antenna with a horn feed for wide-angle scanning is presented,in which the horn's phase center need not be found out and its optimal position can be determined.It is found from numerical calculation that the shaped spherical reflector antenna has better electrical performance than that of the spherical reflector antenna,at the maximum gain value under the conditions of the same feed and reflector aperture,and can be used as a wide angle searching antenna.

Design and Construction of Axial Mode Mono-Filar Helical Antenna for Hydrogen Line Emission Studies with 4NEC2 Tool

Antennas have come to play a significant role in the reception and transmission of electromagnetic radiation or signals which in turn have improved scientific research in the various areas where they have been used. Astronomy is not left out;as a study of everything beyond earth’s atmosphere, useful signals have to travel great distances to reach us. Hence the need for equipment to detect such signals. The Helical Antenna is known to possess high gain (directivity) and can process signals with any type of orientation/polarization which implies high sensitivity hence the desire to use it. Simulation was done using the legacy 4NEC2 software. The purpose of this paper is to design a circularly polarized helical antenna operating in axial mode that is suitable for detection of neutral hydrogen line emission at the frequency of 1420 MHz and to show how it can be used as a feed for an off-set parabolic dish.

基于稀疏采样的FDTD/TDPO混合优化算法

基于时域有限差分(finite-difference time-domain,FDTD)和时域物理光学(time-domain physical optics,TDPO)的混合算法提出用稀疏采样优化近场外推的方法,解决了大口径反射面天线电磁计算用时过长、计算效率低的问题。传统混合算法中馈源的近场外推到反射面天线的步骤计算量较大,稀疏采样法从空间和时间两个维度进行间隔采样,减少了此步骤的计算量,从而节省了用时。给出了馈源为喇叭天线、抛物面口径为100个波长的抛物面天线算例,所得计算结果与传统方法相比最大相对误差仅有-36.03 dB,用时最快可缩短为原来的2.51%,与CST软件计算结果对比吻合度较高,用时缩减了93.18%,验证了本文优化算法可在不影响计算精度的前提下提高计算效率。

Compound parabolic concentrator applied as receiving antenna in scattering optical communication

The two-dimensional（2D） compound parabolic concentrator＇s（CPC） characteristics are analyzed.It is shown that CPC＇s height is taller and its light collecting ability is stronger with the CPC＇s field of view decreasing when the bottom radius is unchanged.According to the ZEMAX analysis,CPC is good at collecting optical signal,and the antenna combining CPC with hemispherical lens can gather more optical signal than a single CPC or CPCs combined in series.The light propagation of scattering optical communication based on multiple scattering is simulated by Monte Carlo method,and the results show that using CPC as receiving antenna can strengthen communication system＇s signal collecting ability and increase its communication distance.

Design and analysis of bidirectional deployable parabolic cylindrical antenna

A bidirectional deployable parabolic cylindrical reflector for an L-band synthetic aperture radar is presented in this study, in which a self-deployed antenna with low weight was designed. The antenna consists of four curved surfaces formed from thin sheets of composite materials connected by hinges along the edges, and the reflective surface is provided by the front surface. The edge profiles of connecting lines were obtained through geometric analysis. A scaled model, including design and manufac- ture, was demonstrated to validate the process from the folded state to the fully deployed state. The non-contact synchronous vision measuring method was used to test the basic frequency of the scaled model, and the test results gave the verification of the analyses. Compared with the existing unidirectional deployable antenna, this new type of bidirectional deployable antenna can be applied to larger-size antennas and has better performance because the glass-woven tape connections were substituted with more reliable hinges. Static, modal, harmonic response, and transient response analyses of the full-sized reflector structure were mod- eled with the commercial finite element （FE） package ABAQUS. The modeling techniques were developed to predict the struc- tural dynamic behavior of the reflector and the results showed that the first natural frequency was 0.865 Hz, and the reflector structure had good stiffness in three directions. This proposed structure has very high stiffness-to-mass ratio because of its hollow solid construction. A preliminary simulation of radiation properties of the parabolic cylindrical antenna, fed by an off-set linear feed horn array, was conducted to obtain the radiation pattern of the feed and the reflector.

基于同频抛物面天线阵列的空间功率合成仿真

以同频抛物面天线阵列为研究对象,以单个抛物面天线口径满足远场条件为工作场景,对天线阵列进行了空间功率合成算法的模型搭建与仿真分析。在算法建模中,构建以正六边形天线阵列为发射天线组阵对象,将各发射天线视为点源,到达接收面的波束为平面波束,计算接收面上各点对应各天线波束与发射天线口径法线间的波束角,根据发射天线的极化方向与波束方向推导出接收点处的场强方向,并将场强矢量分解于三个坐标轴上,同时考虑天线场强的波动行程相位偏移,结合波动方程参与功率合成计算。最后,通过仿真对空间功率合成算法进行了验证,为空间功率合成研究提供一种新的方法。

Theoretical analysis of a parabolic torus reflector antenna with multibeam

The parametric equations and the formulas of unit normal vector and surface element for aparabolic torus reflector antenna are derived and the mechanism of producing multibeam is proposed, Based on physical optics, the radiation pattern formulas for the antenna are given, with which the effects of geometric parameters on the antenna are studied. The good agreement between the calculated patterns and the measured ones shows that the theory is helpful for designing parabolic torus antennas.

一种多频段双波束超宽带测向天线设计

设计了一种多频段双波束超宽带测向天线,通过采用切割抛物面多馈源形式,涵盖L/S/C/X频段,不仅节省设备平台的空间,又能实现多频段双波束共用抛物面,利用结构上改变抛物面切割形式来达到压窄方位面波束的目的。采用馈源偏置的抛物面天线,可以将馈源、馈线、支撑结构等从反射波很强的区域移开,减少对口径面的遮挡,从而改善匹配、降低副瓣电平,实现了多频段双波束共用反射面的设计。测试结果表明天线在L/S/C/X频段范围内电性能良好。

大型可展构架式星载抛物面天线结构设计

提出了一个利用伸缩杆驱动的六棱柱展开单元，和国内外已有的设计相比，该单元可动机构数较少，展开可靠度高，结构刚度好，且具有很广泛的几何适应性，能容易地构造复杂二维可展结构，具有广泛的应用前景。利用伸缩杆六棱柱单元，设计了一大型构架式切割抛物面天线，并简要介绍了天线的可展节点细部设计杆件分类统计。该天线的形面精度较高，质量轻，造价低。最后，对天线模型进行了结构分析，说明天线具有良好的刚度。

航天器可展SAR天线结构综述

论述了航天器径向肋式、缠绕肋式、构架式和环形桁架式四种抛物面可展SAR天线结构的研究现状,分析了四种抛物面可展SAR天线结构的特点,分别对航天器翼式、桁架式和薄膜式三种平面可展SAR天线结构进行了综述,指出了航天器可展SAR天线结构轻质、大收纳比和高精度的发展趋势,提出了航天器可展SAR天线实现展开高精度需攻克的关键技术,旨在为航天器可展SAR天线结构的创新发展提供参考。

超宽带Cassegrain双反射面天线研究

为了减小馈线损耗和方便天线旋转，设计了超宽带Cassegrain双反射面天线系统。采用FEKO数值模拟软件在0．2～1．5GHz频率范围内模拟了不同副反射面直径的4．5m双反射面天线（焦径比为0．4）的辐射增益，并与相同口径和焦径比的前馈式反射面天线进行了比较。模拟结果表明：当双曲副反射面直径为70cm，焦距为22．5cm时，在0．2～1．0GHz频率范围内，双反射面天线增益比前馈式抛物面天线高1～2dB；在1．1～1．5GHz频率范围内，双反射面天线增益比前馈式抛物面天线小1～2dB。选择直径为70cm、焦距为22．5cm的双曲副面与TEM喇叭和4．5m抛物面组成双反射面天线系统，分别用960 ps和3 as脉宽的单极脉冲源对天线进行了实验研究。实验结果表明：用960 ps和3 as脉宽的单极脉冲激励，Cassegrain双反射面天线在70m轴上远场辐射场波形峰峰值分别为前馈式反射面天线的158％和162％。

基于抛物面天线阵的空间功率合成技术

为提高微波空间合成的效率和经济性,提出了一种基于抛物面天线阵的空间功率合成技术。采用抛物面天线作为天线阵列的基本辐射单元,综合考虑空间功率合成效率和相位一致性之间的关系,通过数值分析和理论公式对比得出:合成效率只与单元的幅度和相位有关,与合成单元的数量无关。对阵列单元、天线阵的合成效率进行了软件仿真,得到的合成效率约为92%。结合实验结果,分析了影响合成效率的因素和提高合成效率的方法。

构架式可展开网状抛物面天线反射器设计和分析

介绍了一种构架式网状可展开抛物面天线 ,它具有展缩比大 ,质量轻和频段宽等特点 ,可用作小卫星合成孔径雷达天线和其它S、L频段星载通信天线。设计天线的展开尺寸为 2 8m× 6m ,工作在S频段 ,带宽大于 10 0MHz。介绍了天线反射器的结构总体方案和关键部件的结构设计 ,同时对反射器的形面精度、热变形以及刚度等指标进行了分析计算。初步试验结果表明 。

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。

偏馈抛物面天线方向图外场测试分析

基于口径场法,提出了地基偏馈抛物面天线方向图的数值计算模型,分别给出了自由空间和镜面多径反射情况下的偏馈抛物面天线方向图,分析了测试距离对水平和垂直方向图的波瓣分布和增益的影响;同时分别仿真了固定测试距离情况下,偏馈抛物面天线镜面反射方向图随仰角和高度的变化规律。外场测试结果验证了仿真模型的正确性。该仿真模型能解释不同测试条件下,天线外场方向图的波瓣分布特点,对天线外场测试设计、性能评估和测试误差分析有一定的指导意义。

一种多波束抛物面天线的设计与分析

应用物理光学方法对用于卫星通信的多波束抛物面天线进行了设计与分析,提出了任意形状口径面的处理思想,可方便、有效地计算口径面形状任意、馈源数目任意、馈源放置位置任意的多波束抛物面天线的方向图.最后,用波束优化思想对馈源尺寸及位置进行不断调整,从而使各波束半功率波瓣宽度及偏焦角度达到设计要求,并给出了各组波束方向图.将给定馈源尺寸的抛物面天线的计算结果与GRASP软件仿真结果比较,具有良好的一致性.