星载智能天线结构的机电热耦合优化分析

基于提高星载智能天线电性能和降低作动器能耗的目的,提出了一种以天线增益和作动器能耗为目标函数的结构、电磁、热耦合优化模型,其中约束条件包括杆件结构强度、作动器结构强度和作动器主动行程等,并把太阳热辐射作为初始外载荷.8m天线在六种不同工况下的耦合优化分析结果证明了该机电热耦合优化模型的有效性.     

智能天线结构形状最优控制

为使嵌入作动器的智能天线结构处于最佳工作状态,针对智能抛物面天线结构,建立了以反射面的半光程差的平方和为首要目标,以作动器能耗最小为次要目标的分层优化模型。优化模型同时考虑了结构强度约束和作动器性态约束,模型转化为两个序列二次规划问题进行求解,实现了对智能抛物面天线的准静态形状最优控制模拟。对某10米天线简化平面结构进行了最优调控和讨论。按该模型进行调控,可以实现天线的任意方向的任意载荷下的保型调控,并使调控能耗为最小。     

基于全空域跟踪的椭球型天线桁架设计及标校方法

为满足某卫星工程的测控需求，进一步提高测控网综合测控能力和覆盖范围，提出了一种新型空间椭球天线桁架结构形式及标校方法，满足了全空域、大跨度和高精度的要求。依据大跨度空间桁架理论及有限元分析结果，采用单层空间椭球面网壳的天线桁架构型，通过优化杆件截面、网架形式、跨度和高度等参数实现了对天线桁架承载力的有效分配，合理设计了空间椭球桁架结构及连接方式，并进行了椭球型天线桁架的加工。通过现场测试标定与系统联调，设计加工的椭球型天线桁架达到了系统整体的接收G/T值、第一旁瓣、差波束零深、位置精度和高刚度要求，解决了大型阵列长期运行中定期频繁标校难题，对大尺度阵列天线桁架的设计具有一定的参考意义。     

空间直径为10m的可展开天线

描述了用于空间人造卫星的大型可展开天线，该天线工作于L、C及Ka频段。主反射器的直径为10m，它是利用文中一名作者提出的张力桁架概念而构成的。本文对天线的机械结构作了简单的说明，并对天线的电气设计及电气特性验证方法进行了详细的描述。此天线已成功发射上天，并于1997年在空间展开，主要承担着空间VLBI任务。     

电磁窗桁架阻挡比对天线口径场影响分析

基于感应电流率理论, 提出了将阻挡面积与口径场分布相结合的阻挡比计算方法, 修正了传统算法存在的入射场分布不均匀问题, 分析了金属桁架电磁窗中金属桁杆的散射效应, 研究了桁架阻挡比在特定天线口径场分布下对天线传输特性的影响, 以卡塞格伦天线为例计算了平行极化波入射桁杆阵列时的插入损耗, 并将计算结果与FEKO软件中矩量法仿真结果进行了对比验证.结果表明:考虑天线口径场的阻挡比算法相比传统算法在计算精度上有了较大提高, 最大误差不超过0.1 dB; 金属桁架电磁窗的插入损耗不仅受阻挡面积与感应电流率的影响, 还与天线口径场能流密度分布有关; 减小阻挡比, 是设计低损耗电磁窗的有效途径.     

制造大型空间可展开射电望远镜的基本原则

对制造大型空间可展开射电望远镜提出了一系列的问题并选择了主要解决方法,而且对天线系统和支撑桁架结构提出了设计构思。     

一种大型桁架卫星通信天线座架的优化设计

针对一种大型桁架卫星通信天线座架,对其结构优化设计进行了简要介绍。其中包括天线主座架结构件的形式的优化、关键部件的驱动装置、同步装置、轴系精度的设计,并采用有限元方法对天线结构模型进行了力学分析计算,保证了在工作风速下可以满足天线高精度的要求。通过天线长期的工作数据表明,优化设计后的天线座架结构各项特性均优于设计要求。可为其他桁架天线的结构设计提供技术参考。     

一种基于多维均匀采样与Kriging模型的天线快速优化方法

天线优化设计中,由于经典优化算法一般需要对同一结构的成百上千组参数进行电磁仿真后才能得出最优结果,因此多参数、大范围的天线优化设计存在计算效率问题。该文利用Kriging模型拟合参数空间内样本点的电磁仿真数据,代替电磁仿真实现从结构参数到电磁响应的瞬时近似计算,通过初始阶段的多维均匀拉丁超立方采样算法(LHS-MDU)和优化循环中的新增采样策略,减少电磁仿真次数,提高优化设计效率。利用此方法调整矩形贴片天线的馈点位置和双频单极子天线的振子长度来优化工作频点与阻抗带宽,相比遗传算法,完成相同目标所需的电磁仿真次数分别减少了75%和84%。     

平面隙缝阵列天线的宽带电磁散射特性分析

 针对主动雷达导引头对防空导弹武器系统制导雷达站检测与识别的需求,研究了平面隙缝阵列天线的宽带电磁散射特性.将天线的电磁散射机理与目标高频散射中心理论相结合,建立了天线的电磁散射模型,分别采用矩量法和物理光学法计算天线的模式项散射场和结构项散射场,并从理论上证明了天线散射中心的客观存在,分析了隙缝阵列天线的散射中心分布特征.最后对不同视角下天线的高分辨距离像进行了仿真,为进一步理解天线的电磁散射机理、分析其宽带电磁散射特性、以及采用高分辨率成像技术对雷达站进行检测与识别奠定了基础.     

盆架状压电宏微平面作动器半解析性理论建模

为丰富宏微平面运动装置形式,该文提出了盆架状压电作动器。设定盆架状结构的一阶面内对称弯振模态和二阶反对称纵振模态为工作模态,利用粘附于盆架状作动器表面的压电陶瓷激发工作模态振动,迫使驱动足同时沿xOz、yOz面做椭圆轨迹行进以推动移动体。根据传递阵力学原理,构造作动器各单元的振动传递方程,在确定各单元间连接与传递条件及作动器压电边界条件基础上,建立了作动器的半解析性机电耦合传递矩阵模型,编制了模型的解算程序。建立作动器的多目标优化数学模型,求得其优化结构尺寸。为印证半解析理论模型,还构建了作动器的机电耦合有限元数值模型。传递阵模型与数值模型解得的作动器工作模态频率差分别为177 Hz和191 Hz,求取驱动足在x、y、z向的振幅分别为2.95μm、3.27μm、1.37μm及3.12μm、3.61μm、1.82μm,表明了半解析模型的有效性。结果表明,该文提出的结构设计与驱动原理相结合的作动器分析方式,为优化压电作动器性能开启了新思路。     

基于电磁带隙结构的微带天线小型化设计

提出了一种确定电磁带隙结构慢波波长的分析方法,利用电磁带隙结构支持慢波传播的特性,设计了一种小型化微带天线。以"*"型电磁带隙结构作为接地板,增大了天线的相对电长度。天线工作于2 GHz,相对带宽为2.57%,最大增益为5.45 dB,相比于传统天线,该天线的尺寸减小了40%,带宽有了一定的提高。最后,进行了天线的实物制作和测试,天线的实测结果和仿真结果吻合良好。     

Improvement of bandwidth and efficiency for directive superstrate EBG antenna

The criteria of bandwidth and gain are of prime importance for high rate wireless systems. The electromagnetic bandgap (EBG) antenna, which could be a good candidate for microwave and millimetre link systems, is regarded as a promising solution to achieve a directive antenna with high gain but limited to a narrow band. Presented is a solution to increase the above performances using a three-dimensional antenna structure associating EBG materials technology and that of the metallic waveguide one. The calculated and measured performances of the optimised antenna at 38.9 GHz confirms an improvement of bandwidth (from 150 MHz to 1 GHz) and efficiency (from 20 to 47 ).     

An electromagnetic bandgap resonator antenna

This paper introduces a new explanation of the electromagnetic bandgap (EBG) material properties using the study of the EBG structures in the frequency domain and reciprocal space. Once the behavior of such a material is understood, the properties of the EBG are used in order to make an EBG antenna. The antenna is realized with dielectric EBG rods. Its directivity is increased compared to a simple patch antenna. Such a device allows us to obtain a high gain with a very thin structure.     

准八木型宽带微带天线单元的设计

利用三维电磁场仿真软件(Ansoft HFSS)对准八木型微带天线单元进行了仿真计算.研究了天线结构参数对天线性能的影响.最后得到一个良好的设计。实验结果与计算值相吻合。     

宽频带盘锥天线的研究与设计

设计了一款工作于700MHz～3GHz的宽频带盘锥天线。在参考现有文献得出盘锥初始模型的基础上,通过高频电磁场仿真软件HFSS对各参数进行参数优化仿真,最终得出最佳值。该天线在700MHz～3GHz的频段内VSWR<2,H面辐射方向图具有全向性,并最终通过仿真和实测验证了其性能。     

Research on dual-polarized circular waveguide antenna fed by L-shaped probes

This paper researched a kind of dual-polarized and cylindrical waveguide antenna fed by two L-shaped probes at the antenna bottom. The designed antenna was composed of two orthogonal L-shaped coaxial probes and a cylindrical waveguide cavity. The two orthogonal field structures were excited and the dual-polarized radiation mode was formed. The feeding cables of two polarization ports went through the bottom of the cylindrical cavity and were connected with the microwave adaptors. The bottom feeding structure was suitable to constitute a planar antenna array. The electromagnetic simulation and optimization design of the proposed antenna were carried out by using the full wave electromagnetic simulation technique, and the simulation results showed that the isolation between two polarization ports were more than 20 dB within the frequency range of 4.8–5.4 GHz. At the center frequency, the cross-polarization levels of radiation pattern were lower than −21 dB at the boresights and the beam width of radiation patterns at E-plane and H-plane were more than 70° for two polarization ports. The designed antenna in this paper was fabricated and measured. The measurement results indicated that the designed antenna achieved anticipated radiation performances and design effectiveness of the dual-polarized antenna in this paper was proved. The dual-polarized and cylindrical waveguide antenna is suitable for some application fields such as dual-polarized array radar. The research results in this paper can provide a technical basis for the practical engineering application.     

Antenna Miniaturization Using Magnetic-Photonic and Degenerate Band-Edge Crystals

Engineered materials, such as new composites and electromagnetic bandgap and periodic structures have been of strong interest in recent years, due to their extraordinary and unique electromagnetic behaviors. This paper discusses how modified materials, inductive/capacitive lumped loads, and magnetic materials/crystals are impacting antenna miniaturization and performance improvements (e.g., bandwidth and gain reduction, multi-functionality, etc.). Dielectric design and texturing for impedance matching has led to significant size reduction and higher-bandwidth low-frequency antennas, for example. The recently introduced magnetic-photonic crystals (MPCs) and double band-edge (DBE) materials, displaying spectral nonreciprocity, are also discussed. Studies of these crystals demonstrated that magnetic-photonic crystals exhibit the interesting phenomena of (a) drastic slowing down of the incoming wave, coupled with (b) significant amplitude growth, while (c) maintaining minimal reflection at the interface with free space. The phenomena are associated with diverging frozen modes that occur around the stationary inflection points within the band diagram. Taking advantage of the frozen-mode phenomena, we demonstrate that individual antenna elements and linear or volumetric arrays embedded within the magnetic-photonic crystal and double band-edge structures allow for antenna sensitivity and gain enhancements     

车载天线射频系统电磁干扰的仿真与抑制

整车平台上电子设备密集,通过电磁仿真得出射频天线系统间的干扰矩阵表,分析了系统间的干扰源、电磁干扰裕度,并利用空间隔离、添加滤波器、调整接收频谱等优化措施,抑制各射频天线系统间的干扰,降低车载射频设备的电磁兼容风险。     

Problem Solving in Electromagnetics, Microwave Circuit, and Antenna Design for Communications Engineering (Warnick, K. and Russer, P.; 2006) [Reviews and Abstracts]

Students and researchers have always seen classical electromagnetic theory as a hard-to-digest concept. In this book, attempts have been made to explain the facts in an approachable manner. The contents of this book have been divided into two sections. The first half is the theoretical part, and the second half contains applications and numerical methods. Topics covered include: the fundamentals of differential calculus, a brief review of basic electromagnetics; potentials and wave concepts; the concepts, methods, and theorems about the distribution of electromagnetic energy through space; static and quasistatic fields; the analysis of various waveguides' classical transmission-line theory; resonant circuits and resonators; microwave circuits; periodic structures and filters; radiation from dipoles; antenna basics; and numerical methods used in solving electromagnetic problems.     

舰载多天线系统的耦合特性分析及防护

为解决舰载多天线系统间的电磁干扰问题,应用FEKO仿真软件进行了舰船与天线的全尺寸仿真模型;基于S参数原理与微波网络理论,给出了多天线系统的耦合度表达式;并分别计算了自由空间与舰船载体2种情况下,多天线耦合度的变化规律。结果表明,谐波、天线间距、天线频率及天线周围散射体是影响舰载多天线耦合特性的因素。并基于上述研究,给出了相应的电磁防护建议。本文研究成果可为后续共享铁塔电磁兼容性分析及多天线布局优化提供参考。