Radiation losses in microstrip antenna feed networks printed on multilayer substrates

The effect of the substrate structure on the radiation properties of microstrip array feed networks is investigated with the space-domain integral equation approach. Numerical and analytical techniques are employed to produce efficient computer algorithms. Results for space and surface wave losses are presented for corner discontinuities printed on substrate/superstrate, and two-layer substrate structures. Comparisons are made with the single-layer case.     

Full-wave solutions to the propagation characteristics of buried microstrip lines by VFEM and ABCs

The propagation factors of buried microstrip lines are considered. The associated eigenvalue problems are solved by the edge-based vectorial finite element method (VFEM). To improve the higher-order VFEM solutions, the problem infinite domain is truncated by second-order absorbing boundary conditions (ABCs). This reduces the number of unknowns and, consequently, the numerical effort. Owing to the many advantages of both the edge-based VFEM and the second-order ABCs, this full-wave method is implemented by a general computer program for solving unbounded domain problems involving complex geometries and inhomogeneous media. The examples presented show the validity of this technique. © 1998 John Wiley & Sons, Ltd.     

抑制非平行微带线间串扰的保护带方法研究

非平行传输线之间的耦合(串扰)是非常复杂且难以预测的,但是在高速电路中,这种串扰影响又必须考虑在内.针对非平行微带线串扰问题,首先利用基于Daubechies小波函数的MRTD方法计算非平行微带线间夹角分别为0°、30°、45°、60°时微带线的串扰,提出微带线间夹角对串扰的影响.其次,研究了采用保护带的方法对非平行微...     

The method of lines for the analysis of composite‐metal lossy microstrip lines

A full‐wave analysis of the composite‐metal microstrip lines is presented. The effects of the composite metal to the loss of the microstrip lines are accurately investigated, which are often avoided by other methods. The metal layers of the microstrip lines are considered as lossy inhomogeneous layers. The effects of the thickness of the Au layer and Ti layer are given, respectively. And the reasons that lead to the differences between them are discussed for the first time by analyzing the longitudinal electric field on the strip. The results are compared with other published data. Copyright © 2010 John Wiley & Sons, Ltd.     

Modelling of photonic bandgap devices by the leaky mode propagation method

Main modelling approaches used for investigating the Photonic bandgap (PBG) devices are reviewed. In particular, the model based on Leaky Mode Propagation (LMP) method is described. A complete analysis of the propagation characteristics, including the determination of modal propagation constants, electromagnetic field harmonics and total field distribution, transmission and reflection coefficients, total forward and backward power flow in the structure, guided and radiated power, and total losses, can be carried out by a computer program based on the LMP approach. The numerical results have been validated by comparisons with those obtained by using other more complex and expensive models. The new model shows some significant advantages in terms of very low computational time, absence of any a priori theoretical assumptions and approximations, capability of simulating the actual physical behaviour of the device and fast determination of the bandgap position.Copyright © 2003 John Wiley & Sons, Ltd.     

Controlling the input impedance of a microstrip patch antenna without additional matching elements

Two known methods of controlling the input impedance of a microstrip end-fed patch antenna are investigated and their results are compared. Using a 4 GHz reference antenna, the variations of input impedance and radiation patterns are compared, for (a) changing the feed positions to the non-radiating edge against (b) changing the width of a normal fed patch antenna. An expression for finding the necessary width for the last case is given using the results of the analysis.     

A new approach to analyze a resistive patch antenna excited by a microstrip line and printed on an anisotropic substrate with superstrate

An improved model is presented to study the effect of a superstrate on a resistive rectangular microstrip antenna fed by a microstrip line and printed on anisotropic substrate. A new accurate computation with different unknown currents of the electric field on overlap, feed line and resistive patch is studied by the Fourier transform, considering the Galerkin’s method and entire domain basis functions. Additionally, the scattering radar cross section (RCS) was studied for this novel resistive patch taking into account the effect of the nonzero surface resistance, the superstrate and the anisotropic substrate. To determine the unknown current modes on the patch, the electric field integral equation can be discretized into a matrix form that incorporates the effect of the superstrate, the anisotropic substrate and the currents on the feed line which are efficiently developed. Moreover, the necessary terms to represent the resistive patch are derived and are included in the equation in the form of a resistance matrix. RCS reduction is obtained for high superstrate thicknesses and low superstrate permittivities. Also, the addition of a resistance on the surface of the patch antenna provides a scattered energy diminution. Moreover, the RCS of this novel structure is affected by both \(\varepsilon _z \) and \(\varepsilon _x \) permittivities change, however, has drastically changed due to the \(\varepsilon _x \) permittivity change. In order to validate the theoretical results, a study has been achieved for a perfectly conducting patch on isotropic substrate, without superstrate and excitation, and the results were compared well with other papers. This subject has not been treated or reported previously in the literature, and there has been very little work on the scattering RCS of only simple perfectly conducting patch antennas.     

介电常数测量的微带短路线法及实现

阐述了用微带短路线法,通过矢量网络分析仪量测短路微带线的反射系数,进行印刷电路板板材相对介电常数计算的方法.在给定的板材尺寸参数及材料特性下,通过ADS软体中进行的理论分析以及ANSOFT公司HFSS软体中进行的三维建模仿真分析,计算得出了不同频率点对应的相对介电常数值.同时分析了方案的误差对于阻抗设计的影响,进而验证了测量方案的可行性.考虑到板材介质的高频衰减,测量方法适用范围从100 MHz～5 GHz.     

基于自适应滚动匹配预测修正模式的光伏区间预测

为解决传统点预测方式难以量化光伏发电功率不确定性的问题以及提高预测精度,提出一种基于自适应滚动匹配预测修正模式的光伏区间预测方法.通过结合小波能量的谱聚类方法对历史光伏数据集进行聚类,构建不同类别的模型输入和区间输出并采用宽度学习系统进行训练;建立不同类别、不同置信区间、不同预测功率区间的stable误差分布,并结合优...     

基于阻抗匹配模式的并联逆变器均流方法

针对逆变器并联系统的动态均流问题,提出了阻抗匹配模式的逆变器并联控制方案.依据电路等效理论,将开环控制的逆变器等效为给定电压源与虚拟阻抗串联的电路形式,并给出了阻抗参数的辨识方法.以逆变器的等效电路作为被控对象模型,推导出可改变逆变器输出虚拟阻抗的控制方法.给出了并联逆变器间的虚拟阻抗匹配关系.所设计的逆变器除需共享电压给定基准正弦信号外,完全自主均流,控制方法简单.采用两台容量为1 kVA、空载输出电压为220V的逆变器并联进行了仿真和实验研究.仿真与实验结果显示:两台逆变器输出电流之差峰值小于0.1A;在负载阶跃变化中,无过渡过程.     

配电网馈线的状态估计研究

对配电网馈线的状态估计进行了研究,运用馈线小系统划分形成完整的馈线数据以利于实现其它相关功能,利用馈线的辐射状拓扑结构和负荷点之间存在的弱耦合,采用支路观测点深度搜索定位,使检测数据更加准确,可信度更高。     

湖南省输电线路覆冰舞动预测技术研究

本文在总结大量文献并结合湖南省的气候、微地形等情况的基础上分析湖南省电网输电线路导线覆冰舞动的形成因素、发生机理以及防舞措施。通过总结历史数据,找出湖南电网线路舞动受气候、微地形等因素的影响。首先根据易发生舞动的地形、气候条件,提出合理的避舞措施,即选择合适的线路走向;然后提出合适的抗舞措施,即从提高导线电气和机械强度入手提高线路防舞性能;最后提出相应的抑舞措施,即从改变舞动条件入手,在线路上安装防舞装置的措施。文章最后总结舞动与线路线型、走向等电网结构的关系,提出舞动预测技术,为湖南省线路覆冰舞动预警,提前采取融冰、除冰等措施,进一步减小舞动对线路的危害。     

A computer-aided design of EMC microstrip dipole arrays using nonlinear optimization techniques

This paper describes a method for designing electromagnetically coupled (EMC) printed dipole arrays. The advantages of EMC dipoles include greater bandwidth, higher efficiency, and an easier match to the feed lines, when compared to classically fed printed antennae. The excitation mechanism is provided by a strip transmission line embedded inside the substrate which couples energy parasitically to the microstrip antenna. Electromagnetically coupled microstrip dipoles have been investigated by empirical or approximate analysis techniques. As a result an approximate model has been derived for microstrip dipoles. The method is based on the method of moments solution to an integral equation derived from the approximate Green function for a grounded dielectric slab. The element lengths and offsets and the stub length of the EMC dipole array are determined by the direct search optimization method of Hooke and Jeeves. To show the feasibility of the proposed method, a mathematical formulation and numerical results are presented for Chebyshev arrays. © 1998 Scripta Technica, Electr Eng Jpn, 125(4): 60–66, 1998     

Observation of lightning phenomena on distribution lines using composite techniques

For the rationalization of lightning protection design of distribution lines, it is important to clarify the behavior of distribution lines when direct or nearby lightning occurs. Because of the lower insulation level than for transmission lines, in studies on lightning protection design of distribution lines, not only direct lightning strokes but also induced voltages caused by nearby strokes must be taken into account. Thus, it is necessary to grasp the frequency of occurrence on lightning phenomena around distribution lines. For this aim, lightning phenomena on TEPCO's distribution lines in use had been continuously observed for 6 years (1996 to 2001). The observation was carried out in a composite way, using still cameras and sensor for acquisition of lightning surge waveform data. Through the observation, new phenomena about lightning performance on distribution lines in the field became apparent. In some cases, in spite of a direct strike to the line, flashover did not occur. This fact means that the distribution line has a certain level of lightning resistance. Moreover, it was confirmed that AC following current generated between both ends of insulator disappeared naturally. These results are interesting discoveries that can be useful in estimating the fault ratio precisely. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(1): 10–19, 2006; Published online in Wiley InterScience ( http://www.interscience.wiley.com ). DOI 10.1002/eej.20164     

基于转台的中场ISAR成像技术研究

在中场区通过对相位弯曲补偿进行微波成像与远场成像效果相当,且能大大降低对测试距离的要求,所以具有很强的工程应用价值.基于经典的转台成像模型,本文提出球面波聚焦卷积积分法和中场滤波-逆投影算法,实现了中场区目标的微波成像.球面波聚焦卷积积分法能实现360°范围的二维成像,且运算速度快,适用于各向同性目标,中场滤波-逆投影算法针对小转角范围内对目标进行精密的二维成像,适用于各种复杂目标.仿真和实验结果表明,这两种算法的有效性.     

多层印刷电路板技术在VXI总线背板中的应用

介绍了用普遍的PROTEL软件完成复杂的十二层印刷电路板的设计，用于VXI总线背板，保证总线传输的准确性和可靠性，提高抗电磁干扰的能力。     

A generalized CAD model for the full‐wave modelling of microstrip line and its regular and irregular discontinuities

In this paper we present a new theoretical model for the modelling of the microstrip line as well as two types of discontinuities: regular (open end, step, bend and T‐ and cross‐junctions) and irregular (stub and bent‐stub). The two‐dimensional exact dyadic Green function of a grounded dielectric slab has been used with the Galerkin's technique. The subdivision of the discontinuity in a network of juxtaposed unit cells, characterized by their own longitudinal and transversal current distributions, allowed the treatment of a large class of irregular discontinuities in addition to the regular discontinuities. The obtained results have been commented and compared with those of different approaches and with experimental results where a good concordance has been observed. Copyright © 2006 John Wiley & Sons, Ltd.     

Ka波段自偏置微带边导模隔离器仿真设计与性能

基于M型锶六角铁氧体的高各向异性场,采用HFSS软件设计了中心频率在28.2GHz的自偏置边导模隔离器。仿真结果表明,在28.2GHz附近,插入损耗为6dB,隔离度大于38dB,20dB以下隔离带宽约为3.5GHz。采用传统固相反应法制备SrM六角铁氧体材料基片并用丝网印刷工艺实现基片上的微带电路,根据设计的结构参数制备了自偏置边导模隔离器。测试结果表明,该自偏置隔离器在27~29GHz范围内,表现出强烈的非互易性,插入损耗小于10dB,最大隔离度大于45dB。由于不需要外加偏置磁场,器件实现了小型化,宽频带,仿真与实测吻合得较好。