辐射发射测量天线的校准方法

文章介绍了辐射发射测量所用宽带天线天线系数的校准方法,并对影响测试结果的因素进行分析。     

基于三相幅度测量的相控阵天线快速校准方法

提出了一种基于三相幅度测量的相控阵天线快速校准方法。该方法将天线阵列进行分组,利用每种分组在三种配相下的阵面合成场幅度测量值,可解算出各个天线单元的初始幅相值。该方法仅需幅度测量,避免了相位测量误差影响单元幅相值的计算精度,而且所需幅度测量次数仅为(2N+1)次,可显著提高校准时效性。另外,利用分组思想,同时改变多个单元相位,使总辐射场的幅度变化显著,提升校准准确性。仿真结果表明:校准后相位均方根误差为2.2°,幅度均方根误差为0.2 dB。     

EMC 测量天线系数的校准方法和误差分析

天线系数在EMC 测试中是一项重要参数。然而天线生产者提供的天线系数都是在一定前提下进行校准的, 如果直接使用会带来测量误差。所以必须进行校准。本文介绍几种常用的校准方法,详细阐述了如何用三天线法测量 校准天线系数,并对影响测量结果因素进行分析,给出改进方法。     

射频通信天线的仪器测量校准方法

分析射频通信天线系统的构成模块及各部分的功能，为解决天线系统的实际性能与设计指标相差较大的问题，介绍用射频仪器和常用实验室设备进行参数测量和天线校准的方法。     

宽带天线系数的校准

天线系数校准是一个重要的计量课题 ,也是电磁兼容工作者们极为关注的问题。本文介绍互易法校准宽带天线系数及应注意的一些问题。     

天线系数的校准和使用

天线系数是一项重要参数。然而 ,天线生产者提供的天线系数都是在一定前提下进行校准的 ,如果直接用于测量现场就会带来误差。但若在测量现场先求得天线实际增益 ,便可计算出精度更高、实用而有效的天线系数。     

基于反相测量的有源相控阵天线中场校准方法

提出一种基于反相测量的有源相控阵天线中场校准方法。为使在校准过程中合成辐射场信号变化明显,使用伪Hadamard矩阵将天线阵列进行分组。校准时,将组内相位改变单元反相,将两次测量结果相减得到相位改变单元的总辐射场,最后对分组矩阵求逆并去除程差,即可解算得出阵面幅相分布。仿真结果表明,校准后,通道幅度均方根误差为0.18 dB,相位均方根误差为1.84°,达到校准效果。     

基于网络分析仪的EMC测量天线校准方法研究

首先,介绍了SAE ARP 958D-1999 (R2003)中建议的天线校准方法,指出了该方法具有操作繁琐、效率低和精度不高等问题;然后,提出了基于网络分析仪的简便天线校准方法,该方法利用网络分析仪的S21扫频测试功能,能够一次性地测试得到整个待校准频段的参数,不但可以简化测试操作步骤,提高工作效率,而且还可以提高测量精度和校准精度.     

开阔场环境下场强测量的场地预校准方法

本文根据无线电监测系统开场测试相关标准,对在测试中为提高场强测量准确度而实施的场地预校准所采用的方法和相关要素进行具体介绍和分析,并结合实际案例提出了相应的优化方法。     

多组阵列天线相位校准方法

提出了利用多次幅度测量实现多组阵列天线相位校准的方法,解决了多组阵列在天线辐射方向需要同相位合成的难题,保证了多组阵列实现高效率合成。介绍了校准方法的工作原理,给出了多组阵列天线进行相位校准的工作过程。对校准前后的天线测试结果进行对比分析,得出校准精度符合工程设计要求,且无需调试,易于实现远场自动校准,适用于多组阵列天线研制过程中的相位校准工作。     

Measuring the carrier velocity in a monopulse radar with a synthetic antenna aperture

An algorithm for measuring the carrier velocity in a radar with a synthetic antenna aperture is proposed for the case of a monopulse antenna system. It is shown that, with the use of the azimuthal difference channel, it is possible to substantially increase the accuracy of measuring the carrier velocity in the direction toward the center of the mapped area, even in the case of a substantial shift of the center of the energy spectrum of the received signal from the boresight.     

Biconical antenna and V-conical antenna with elliptic cross section

The methods of coodinates transfomation and conformal maping are applied to the problem of ra diation from a biconical antenna and V-conical an tenna with elliptic cross section. The infinite el liptic cone geometry can be transformed into two dimentions plane under the assumption of pure TEM spherical wave. The Closed-form solutions for the fields, currents, and characteristic parameters are obtained.     

网络报文动态监测仲裁系统设计实现

网络监听作为一种逐步发展和完善的技术,在协助网络管理员监测网络传输数据、分析网络的流量、排除网络故障等方面具有不可替代的作用。系统实现了流水线式模式进行数据包捕获和解析处理。建立了通用的报文捕获与解析方案。系统主要以UDP协议报文数据段的解析为重点,支持点对点、组播报文和广播报文的捕获与解析。报文协议可由用户自行设计,用户可以根据需要设计应用层报文协议,用于监控与分析报文。     

低频天线测量系统中宽带双极化源天线研究

低频天线测量系统中采用四脊喇叭天线作为发射源天线, 为实现四脊喇叭天线在低频段的小型化, 设计了一种新型结构:脊边缘采用铝固体结构, 内部采用蜂窝结构来减小天线尺寸和重量.利用HFSS仿真软件对喇叭天线整体结构参数进行优化, 并对其进行加工测试.仿真和测试结果表明:后腔采用可调短路板可抑制驻波奇异点的出现; 实际加工过程中, 将聚四氟乙烯板填充在四个对称脊中间确保脊的对称性, 并得到良好的电性能.该天线已应用于低频天线测试系统, 在锥形暗室中作为发射源天线来测量汽车天线的方向图.     

大规模MIMO相关信道下的联合天线分组和天线选择

在大规模多输入多输出系统中,针对密集部署的大型天线阵列之间的强相关性会抑制天线选择增益效果的问题。在系统下行链路场景下建立空间相关信道模型,提出了基于天线分组的天线选择算法。根据瞬时信道相关矩阵将天线阵列划分为若干组,保证各组内天线之间相关性较强。在完成天线分组的基础上,基于信道矩阵列范数准则在各组发射天线与接收天线之间构成的子信道矩阵中选择天线,进而构造有效发射天线与接收天线之间的信道矩阵。仿真分析了所提天线选择算法对系统遍历和速率的影响,结果表明,在基站天线数为32、接收天线数为2、选择天线数为2、天线相关因子为0.9的假设下,当信噪比为10 dB时,与基于相邻天线分组的天线选择算法相比,所提算法使系统和速率约提高了27.5%,且所提算法若要与最优天线选择算法达到相同的和速率,仅需将其信噪比提升1～2 dB即可。     

线天线及天线阵的时域传输线矩阵法分析

本文针对线天线及天线阵的频域分析方法的缺点，首次将时域传输线矩阵法应用到这一领域，应用时域ＴＬＭ法时，只需经过一次运逄就可以得到天线及天线阵各个区域的场特性，本文计算方法及数值结果表明，运用时域ＴＬＭ法可以对各种大型天线阵进行有效的分析，便于工程应用。     

Model checking for E-business control and assurance

Model checking is a promising technique for the verification of complex software systems. As the use of the Internet for conducting e-business extends the reach of many organizations, well-designed software becomes the foundation of reliable implementation of e-business processes. These distributed, electronic methods of conducting transactions place reliance on the control structures embedded in the transaction processes. Deficiencies in control structures of processes that support e-business can lead to loss of physical assets, digital assets, money, and consumer confidence. Yet, assessing the reliability of e-business processes is complex and time-consuming. This paper explicates how model-checking technology can aid in the design and assurance of e-business processes in complex digital environments. Specifically, we demonstrate how model checking can be used to verify e-business requirements concerning money atomicity, goods atomicity, valid receipt, and communication-link failure. These requirements are fundamental to many e-business applications. Model checking can be used to test a broad range of systems requirements-not only for system designers, but also for auditors and security specialists. Systems that are examined by auditors need to have adequate controls built in prior to implementation and will need adequate auditing after implementation to ensure that none of the processes have been corrupted. Model checkers may also provide value in examining the processes of highly integrated applications as found in enterprise resource planning systems.     

An optical subarray antenna having antenna nulling applications

A linear subarray type optical antenna is considered for adaptive applications. The antenna has a small number of subarrays whose radiation patterns cover the region occupied by targets and interference in a near-optimum fashion. The subarray design is such that very low subarray pattern sidelobes are produced, thereby allowing operation in the presence of additional strong interference outside the subarray beams. The design of a near-optimum sheet metal antenna to perform these functions is described and the performance is analyzed.     

V-conical antenna

A new angular antenna called the V-conical antenna was investigated. The characteristics of the antenna are frequency-independent, and the electromagnetic fields are pure spherical waves (transverse electromagnetic mode) even in the near region. The theoretical analysis makes use of conformal mapping. Closed-form solutions for the fields, currents, and characteristic parameters are obtained. The formulas are simple and precise. An experimental study of the antenna was conducted under pulse excitation. The shape of the measured electric-field pulses is the same as that of the source pulse from a picosecond pulse generator. The measured field patterns are very close to those predicted by the theory. Such a structure with a tapered resistive termination is an ideal directional pulse antenna or electromagnetic pulse simulator     

智能天线的新军——自组构天线

自组构天线凭借其能够根据所处的电磁环境来改变自身的电形状这一特性, 已成为当今智能天线研究领域的一大热点.文中介绍了自组构天线的概念模型, 详细分析了三种常用的自组构天线的工作原理, 对未来自组构天线的应用和发展方向进行了具体的讨论.