帐篷型小型电波暗室的探讨

文章对有屏蔽特性并使用短碳纤维和电波吸收体的帐篷型小电波暗室进行了探讨。依据所使用的短碳纤维的屏蔽和吸收特性及测试结果并结合帐篷内的配置得知它有50dB屏蔽效果,帐篷内电磁环境稳定和优良,故本帐篷可实现小型电波暗室功能。     

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。     

GALEO线阵列音箱测量与分析

介绍了一种德国小型线阵列音箱,在大型消声室内作了验证性和分析性的基础测量,并对测量结果作了初步分析,提出了几点体会。     

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。     

Direction-of-Arrival Estimation System for Multipath Propagation in Code-Division Multiple-Access Systems With Synthesized Virtual Planar Array Using Pilot Signals

Here, we propose a method for estimating the direction of arrival (DOA) using pilot signals in code-division multiple-access (CDMA) systems. We also report the evaluation of the performance of the proposed method by conducting simulations and experiments in an anechoic chamber and an outdoor environment. This method estimates the DOA of the arrival waves by synthesizing the data received by a virtual planar array using pilot signals. First, we describe a method for synthesizing the data received by the virtual planar array using pilot signals. Next, we present simulation results that confirmed that the accuracy of the estimation based on the virtual planar array was the same as that based on a real planar array. Last, we describe the effectiveness of the proposed system that is demonstrated through experiments in both the anechoic chamber and in an outdoor environment.     

天线阵辐射特性的传输线矩阵（TLM）方法分析

运用传输线矩阵（ＴＬＭ）方法，对由理想点源天线构成的直线天线阵在不同激励方式下的辐射方向图进行了数值计算。计算结果与解析分析结果吻合得很好，说明ＴＬＭ方法可以方便地模拟各种天线阵的辐射特性。ＴＬＭ方法也可以模拟在微波暗室里对天线阵的测量。     

暗室墙面反射对雷达告警系统测向的影响

微波暗室为电磁波的定性分析或定量测试提供一个近似无反射的环境,当微波暗室内存在的反射不能忽略时,暗室墙面反射引起的多路径传输就会影响对测试结果的评定。在阐述比幅单脉冲测向原理的基础上,研究了由于暗室静区反射电平对雷达告警系统测向精确度的影响,建立了暗室静区反射电平与雷达告警接收机测向误差的关系模型,并且结合四元阵、八元阵、十六元阵说明了静区反射电平、来波方向与测向误差范围的关系。     

一种靶弹装配检测雷达系统

位于靶弹弹体内的龙伯球装配正确性与否将直接影响靶弹的使用性能,本文设计一种用于靶弹装配生产线使用的检测雷达系统,该系统采用2.1GHz 频率的连续波体制,结合小型微波暗室的使用,实现靶弹内龙伯球正、反向装配时雷达输出信号电平大小差别10 倍以上,可以有效检测龙伯球装配的正确性,并具有操作简便、体积小、可靠性高、成本低的特点。     

A low-frequency model for wedge or pyramid absorber arrays-I:theory

The interaction of electromagnetic waves with an array of absorbing wedges or pyramid cones is studied in the low-frequency limit; i.e., when the period of the array is small compared with wavelength. A theoretical model is obtained using the method of homogenization, which replaces the transversely periodic structure with a transversely uniform medium possessing a certain (generally anisotropic) effective permittivity and permeability. Plane-wave reflection from such structures can then be modeled using well-known techniques for one-dimensionally inhomogeneous media; a Riccati equation for the reflection coefficient is used in this work. This model is appropriate for use with absorbers found in anechoic chambers used for electromagnetic compatibility and electromagnetic interference (EMC/EMI) measurements over the frequency range of 30-1000 MHz     

天线回转中心偏离阵列球心对测向的影响

在微波暗室内进行射频仿真试验时,必须保证被试装备天线回转中心和天线阵列的球心重合,否则就会引起测向误差,从而影响对被试装备性能的科学评估.分析了对心不准对装备测向测试结果的影响,建立了测向误差的分析模型,并且结合实例详细分析了偏心距离和测向误差的关系.相关分析模型和结论可以作为对心设备建设中对对心精度的指标论证的依据,也可以为仿真试验战情的设计提供科学的借鉴.     

Propagation measurement using antenna array

The design and construction of a 2.4 GHz antenna array suitable for measurement of the time, angle, and complex amplitude of path arrivals in an indoor radio channel are described. Calibration of the array is facilitated with the aid of an anechoic chamber. An optimal least-squares processor is derived, which compensates for systematic calibration errors. Early measurement results are presented, and future direction of the research are indicated     

一种基于四元立体阵的声定向方法

提出了1种四元立体阵列模型,采用时延估计的声定向方法,设计完成了基于DSP的被动声定向硬件系统,经消声室实验验证了方法的可行性。     

无人机通信干扰电磁环境半实物仿真系统

针对战场环境下复杂传播环境及敌方干扰对无人机通信系统性能的影响,提出了综合信道衰落和干扰共同作用下的无人机通信信道理论模型。在此基础上,基于微波暗室设计实现了无人机通信干扰电磁环境半实物仿真系统。该系统利用硬件现场可编程门阵列(Field Programmable Gate Array,FPGA)实时模拟无人机通信信道和干扰信号,利用微波暗室模拟外场的无线传播环境,并通过天线位置和角度调节装置模拟发射机、干扰机和接收机之间的空间位置特性。实测结果表明,该半实物仿真系统能够真实复现无人机通信干扰电磁环境,可用于无人机数据链抗干扰性能的测试和评估。     

MIMOOTA测试系统的校准和验证

从MIMO的特性出发,在全电波暗室内利用多天线探头测量方法,实现了对多天线无线设备OTA的多径环境模拟。给出了OTA多径信道模拟器的校准要求,以及验证测试环境可靠性的方法,满足了设计要求。     

稀疏阵列微波暗室成像实验研究

为了在实际条件下验证稀疏阵列孔径综合方法可以避免稀疏阵旁瓣较高的问题,以及基于压缩感知理论的成像算法可以对具有稀疏特性的目标进行重建,开展了微波暗室实验。针对实验中的阵列误差,给出了具体的校正方法。通过实验数据处理证明了阵列误差校正方法、稀疏阵列孔径综合方法以及基于压缩感知理论成像算法的正确性和有效性。     

Anechoic chamber evaluation using the matrix pencil method

A new method for evaluation of an anechoic chamber using the matrix pencil method is presented. A signal measured between two antennas placed in an anechoic chamber is sliced into small frequency intervals and is processed using the matrix pencil method. In each interval, the measured signal is decomposed into its propagating-wave components, which correspond to a direct propagation between two antennas and reflected propagating waves from absorbing walls. The ratio of amplitudes of the reflected wave components with respect to the direct path propagation gives a new measure of quality factor for an anechoic chamber     

A time-domain method for characterizing the reflection coefficientof absorbing materials from 30 to 1000 MHz

A wideband time-domain reflectometer is used to evaluate the reflection characteristics of RF/microwave absorbers. The reflectometer uses an array of two identical broadband antennas (both transmitting and receiving). The two antennas are used in a difference mode to remove the undesired signals and enhance the small reflections being measured. Using this technique, one can separate the target surface reflection from those generated outside the target area. The bandwidth of the pulses is 30 to 1000 MHz, and the reflection coefficient is measured over this range. The method has been used to characterize the reflectivity of three different types of absorber placed in an anechoic chamber. The results are reported together with a discussion of the main sources of errors     

Mitigation of wing flexure induced errors for airbornedirection-finding applications

Errors in array calibration are the dominant error source for direction finding (DF) in airborne platforms. This problem arises since wings in large surveillance aircraft exhibit significant flexure, and their actual instantaneous positions during array calibration and operational flight is likely to be quite different. Scattering from time-varying wing structures onto the belly mounted antennas therefore causes the array responses to deviate from the array calibration and gives rise to DF errors. We present a simple model for array manifold perturbations due to wing flexure that captures their effect. The model is physically motivated and has been validated using experiments on a scale-model aircraft in an anechoic chamber. Our model can be exploited to derive new versions of the classical DF estimation schemes including weighted subspace fitting (WSF)     

基于MCM法的大型有源相控阵二维阵列校准

MCM法可以在没有微波暗室或外场条件不理想的情况下对大型阵列进行校准。文中将此方法应用于大型有源相控阵二维阵列校准,得到了基于MCM法的二维阵列口径分布推导公式,对该方法应用于二维阵列时的新特点新问题进行了分析,比较了不同推导方式下的阵列性能差异,并进一步对该方法的误差统计特性参数进行了研究,最后提出了MCM法在工程应用中需要注意的问题和应对措施。     

单指向水听器以及双圈十元阵的实验研究

从单指向水听器的定义出发,分析其在水下波束形成中的应用,并利用单指向水听器构建了双圈十元阵这一特殊的基阵模型,以此阵为基础在消声水池进行了实验研究,验证了单指向水听器应用于水下波束形成时的有效性和实用性。从理论、仿真和实测数据处理等各方面都证实单指向性水听器及其应用于基阵波束设计的可行性和优异性能。