Ka 波段紧缩场天线的设计

设计了一个Ka 波段紧缩场天线。馈源设计结合角锥喇叭在反射面边缘照射电平下降快与波纹喇叭波瓣宽度宽的特点,通过给角锥喇叭加扼流套的改进设计来实现对反射面的照射。反射面采用锯齿型边缘来降低边缘的绕射作用,并进一步在无法加工锯齿部位贴附三角形吸波材料来减小绕射对静区特性的影响。暗室内采用平面测量结果表明,Ka 波段紧缩场天线静区特性满足设计指标要求。     

Performance trade-off between serrated edge and blended rolled edgecompact range reflectors

The performance trade-off between serrated edge and blended rolled edge compact range reflectors is investigated. The edge diffracted fields which contribute to stray signals in the quiet zone have to be minimized. Consequently, an iterative approach has been developed to design serrated edges such that the edge diffracted rays from the serrations can be kept as far away as possible from the desired quiet zone area. Performance of various designs based on the number and size of serrations have been studied using a physical theory of diffraction solution. In addition, an optimized blended rolled edge design with the same size as the serrated edge reflector has also been evaluated for comparison. Finally, numerical results are presented in this paper to address the performance trade-off issue among the various designs. It is clearly shown from this study that the blended rolled edge reflector performs significantly better, which should offset the increased cost needed to construct a rolled edge reflector versus a serrated one     

Optimisation of cross-polarisation performance for tri-reflectorCATR with spherical main reflector

For a tri-reflector compact antenna test range (CATR) with spherical main reflector and shaped subreflectors, the cross-polarisation performance is optimised, based on the beam-mode expansion method. For optimal designs, physical optics (PO) calculations of the quiet zone fields are presented, and it is shown that a tradeoff has to be made between a low cross-polarisation level and a low amplitude ripple in the quiet zone     

紧缩场静区校准用超宽带天线性能的分析

紧缩场是天线天线罩辐射特性、目标散射特性测试的重要设备,在使用前需要对其静区平面波幅度锥削、幅度波 纹及相位变化等电磁性能参数进行校准。紧缩场的静区性能校准离不开全频段的探头接收天线,校准天线的性能会影响紧缩 场静区电磁参数的校准结果。文中阐述了校准紧缩场静区性能的扫描法原理,利用本单位研制的紧缩场校准系统,在某研究 所的紧缩场环境内,比较了标准增益喇叭天线与超宽带双脊喇叭天线分别作为接收探头的差异。实验证明,设计完成的超宽 带双脊喇叭天线具有驻波低、增益适中、更换方便、频带宽等优点,完全可以替代六个波段标准增益喇叭天线的功能。     

基于全息的太赫兹紧缩场测量技术

用传统反射面紧缩场法测量太赫兹高增益天线,要求紧缩场的反射面表面加工精度小于百分之一波长,不易制造,且非常昂贵。针对这一问题,介绍了一种新型易于构建的基于全息紧缩场测量技术,简述了全息紧缩场天线测量原理,利用时域有限差分法和物理光学法对全息紧缩场进行电磁场数值计算,并设计仿真了频率为310 GHz的全息紧缩场,所生成的静区幅度波动小于1 dB,相位波动小于10°,能够达到紧缩场测试的要求。     

暗室条件下抗干扰测试结果影响分析

暗室为卫星导航接收机抗干扰测试提供了全面有效的测试环境，极大地提高了抗干扰性能定量测试与评估能力。但暗室的静区性能、结构尺寸、天线布局等因素会对抗干扰性能测试结果产生影响。基于多径信号天线接收模型、阵列波程差等效模型和信号来向天线映射模型，通过仿真量化分析了干扰多径信号、有限距离下近场效应和来波方向误差对抗干扰测试结果的影响。结果表明，暗室静区性能的提升可降低干扰多径信号对零陷位置的拉偏；不同暗室尺寸对应不同的零陷深度测试，需根据测试需求折中选择；布设暗室天线应依据预设的被测阵列天线和测试场景。结果可为暗室设计、抗干扰测试方案选定和测试结果分析提供参考，提升抗干扰测试的可信度。     

微波暗室静区性能仿真预测方法

为了有效预测微波暗室的静区性能,使用FEKO软件进行任意入射角度条件下角锥吸波材料的前向反射率仿真,并以某矩形暗室结构为例,利用吸波材料反射率仿真结果,采用射线追踪法计算了发射天线位于天线阵面上典型位置时暗室静区内反射电平的分布情况.经比较,仿真结果与实际测量结果一致性较好,该方法为微波暗室性能预测提供了有效手段.     

应用于卫星导航与对抗的穹形满天星暗室的仿真设计

针对当前信息化战争背景下卫星导航装备对无线测试环境的应用需求,结合现阶段国内外暗室发展现状,对矩形、穹形两种暗室进行选型分析,从静区特性、应用性能等方面进行系统仿真分析,最终采用穹形暗室作为暗室选型方案。通过满天星天线布局,模拟真实环境中的卫星轨迹和信号,构建与真实环境高度逼真的无线测试环境,能够有效支撑卫星导航装备尤其是波束成形抗干扰终端的测试,填补了国内在穹形满天星暗室方面的设计空白,可指导工程实践应用。     

基于AFA型吸波材料的微波暗室静区性能仿真

基于射线追踪法开发的静区电平仿真软件应用于AFA型吸波材料(难燃型吸波材料)铺设的微波暗室静区性能仿真。软件以国内暗室性能检测机构的喇叭天线数据为依据设定发射天线的辐射特性模拟函数,得到发射天线的直射波方向图。以AFA 型吸波材料的实测数据为依据设定吸波材料的吸波特性模拟函数,计算微波暗室各面墙壁反射电场在静区内叠加后的总反射电场值,并据此得到静区内的反射电平分布。仿真与实测结果表明,1 GHz 以下静区反射电平仿真结果下限值与测试结果偏差相对较大;1 GHz 以上两者偏差小于1 dB,吻合较好。验证了该仿真软件能够快速并较准确地用于微波暗室吸波工程的设计与评估。     

Design and construction of a multipurpose wideband anechoic chamber

An electromagnetic anechoic chamber has been constructed at the Multimedia University. It is designed to operate over a very wide frequency range from 30 MHz through 18 GHz. It can be used for electromagnetic compatibility (EMC) tests, antenna measurements, radar cross section (RCS) measurements, testing RF transceivers, calibration of scatterometers, and other electromagnetic research experiments. The geometry of the chamber is asymmetrical, consisting of a combination of rectangular and tapered volumes. The size of the chamber is about 64 ft /spl times/ 32 ft /spl times/ 24 ft high. Ease of construction and ease of lining of the absorbers were preserved so that the actual quietness is comparable to the theoretical simulation result. The transmitting source is placed at one end of the chamber, and the receiving antenna or object under test is placed in a designated quiet zone at the other end. The walls and ceilings are configured such that no first-order and or second-order reflections (except those reflected from the floor) propagate into the quiet zone. Hence, less-expensive absorbers can be used to achieve the required wideband performance. Reflection from the floor is required by the international EMC standards for radiated electromagnetic interference (EMI) emission tests; therefore, the chamber is designed for this capability. However, absorbing material can be placed on the floor to convert a semi-anechoic chamber into a fully anechoic chamber for radar and antenna measurements.     

Antenna Tests With a Hologram-Based CATR at 650 GHz

A hologram-based compact antenna test range (CATR) is designed, constructed, and used to test a 1.5-m antenna at 650 GHz. The CATR is based on a 3.16-m-diameter hologram as the collimating element. So far, this is the highest frequency at which any CATR has been used for antenna tests. The quiet zone is measured and optimized before the antenna tests. The measured antenna pattern results at 650 GHz are analyzed and compared to the simulated patterns. Feed scanning antenna pattern comparison technique is used to correct the antenna pattern. These tests show the hologram CATR to be promising for antenna measurements up to 650 GHz.     

Hologram-based compact range for submillimeter-wave antenna testing

A hologram-based compact antenna test range (CATR) is being developed to overcome challenges met in antenna testing at submillimeter wavelengths. For the first time, this type of CATR has been built for testing of a large reflector antenna at submillimeter wavelengths. The CATR is based on a 3-m computer-generated hologram as the focusing element. This paper discusses the design and the construction of the CATR, and the verification of the CATR operation with quiet-zone tests done for the CATR prior to the antenna testing. Assembly of the CATR, testing of the 1.5-m reflector antenna at 322 GHz, and the disassembly were all done within two months in 2003. The quiet-zone field measurement results are analyzed in this paper. The CATR was concluded to be qualified for antenna testing. The antenna testing is described in a separate paper.     

Stray signal requirements for compact range reflectors based on RCSmeasurement errors

The authors present a performance criterion for compact range reflectors such that their edge diffracted stray signal levels meet a reasonable radar cross section (RCS) measurement error requirement. It is shown by example that one of the significant error sources is the diffracted fields emanating from the edges or junctions of the reflector. This measurement error is demonstrated by placing a diagonal square flat plate in the target zone and rotating it to appropriate angles. These angles are determined by bisecting the plane wave and stray signal directions. This results in a peak bistatic measurement of the edge diffracted stray signal. It is proposed that the diagonal flat plate be used to evaluate new reflector designs as well as existing systems. A reasonable stray signal performance level has been developed so that new reflector systems can be characterized in terms of an RCS measurement error requirement     

微波暗室静区性能的测量方法

本文给出了使用自由空间驻波法进行微波暗室静区性能测量的基本原理,并以实际测量为例,给出了使用对数周期天线、矢量网络分析仪对一矩形微波暗室静区性能进行测量的详细步骤及检验方法.本文对微波暗室的建设、使用和维护具有一定的指导意义,对使用微波暗室进行天线和微波后向散射测量也有一定的参考意义.     

电波暗室静区性能及设计要点

静区性能是电波暗室综合性能的体现,也是暗室设计的关键.分析了静区性能对试验的影响程度,以此作为确定暗室静区指标和暗室设计的依据,论述了影响静区性能的各种因素以及保证静区性能的设计要点.     

现代谱估计在窄带天线测试中的应用

在暗室中对窄带天线进行测量时,由于间接时域方法的测试带宽不足而无法有效地去除多径信号所产生的干扰,文中提出将现代频谱估计技术应用于此类天线的测试。以最大熵为约束条件,利用现代谱估计中的Burg算法求解接收到频域信号的AR模型参数,并对其进行频谱外推。从而在频域拓宽信号的测试带宽,在时域提高信号的分辨率,并运用间接时域测量技术精确加载时域门,达到去除多径干扰的目的。仿真和实测都验证了该方法的有效性及可靠性。     

Compact range reflector edge treatment impact on antenna andscattering measurements

Compact range measurements with a serrated edge and a blended, rolled edge reflector are compared. This is done by using simulated antenna pattern and backscattered field measurements. The measurement errors caused by stray signals emanating from the edge termination of reflector are discussed. It has been found that different stray signal sources impact on the measurement accuracy from different aspect angles. In addition, the measurement accuracy achievable with different reflector systems is dependent on the characteristics of the antenna or scatterer under test. From these findings, one will be better able to understand how well these two types of reflectors will perform in terms of accurately providing the proposed measurements. Consequently, one will be able to choose the best reflector design for his/her application     

一种基于微波暗室的大角域卫星导航接收机测试场景构建方法

提出了一种基于微波暗室的大角域测试场景构建方法,该方法利用已有42射频面阵,采用多状态联合校准方法对面阵天线单元到接收机的信号幅度和相位进行校准,以及采用灰色关联分析方法将外界环境下的卫星星座、动态干扰在微波暗室内实现逼真映射,构造最大视场角为160的半实物抗干扰测试场景。仿真测试结果表明:暗室天线单元与实际场景下的卫星星座在角域关系下最大误差在高增益3 dB 波束宽度内,暗室模拟的动态干扰与实际环境下到达接收机的功率基本一致;最后实现了对多波束抗干扰接收机的测试,并通过干信比与有效载噪比的关系曲线说明了该方法能够在室内实现导航接收机测试环境的逼近模拟,并准确地测试出多波束接收机的抗干扰性能。     

电波暗室静区性能的分析与评估

文章从反射路径损耗、吸波材料性能、天线波束宽度等三个方面分析了影响暗室静区性能的因素，给出了暗室静度计算模型，较全面地考虑了影响暗室静区静度的各项因素，能够为暗室设计者提供科学的指导。