平台运动引起Bragg海浪谱的展宽及其压缩方法

基于运动叠加原理，推导了以Ｄｏｐｐｌｅｒ频率表征的雷达平台运动条件下高频段海浪杂波的运动方程及由平台运动引起的Ｂｒａｎｎ海浪谱的展宽式，给出了受平台运动调制的Ｂｒａｇｇ浪回波与目标信号在Ｄｏｐｐｌｅｒ域里的二阶模糊关系和动用ＳＴ－ＷＤ（Ｓｈｏｒｔ Ｔｉｍｅ Ａｖｅｒａｇｅ Ｗｉｇｎｅｒ－Ｖｉｌｌｅ Ｄｉｓｔｒｉｂｕｔｉｏｎ；短时间平均Ｗｉｇｎｅｒ－Ｗｉｌｌｅ分布）技术对一阶海浪回波信号的高频相位进     

声表面波延迟线的优化设计

在现代雷达和通信系统中,声表面波延迟线是应用非常广泛的器件,与此同时,对该器件的技术要求也越发严格,以至于常规的声表面波延迟线很难满足。介绍了4种声表面波延迟线的优化设计方法,克服了传统延迟线受器件尺寸和基片材料长度、相对带宽及多路延迟的限制,满足了雷达、通信等电子设备中对电信号的长延迟需求,为声表面波延迟线设计提供了参考。     

EM Modeling of Microstrip Conductor Losses Including Surface Roughness Effect

This letter presents a method to model conductor losses in transmission lines utilizing a commercial full wave solver. The lines consist of multilayered metallization with inherent surface roughness. Metal thickness is assumed to be larger than skin depth. To validate accuracy of the modeling, the measurements of a 50-Omega microstrip line and edge-coupled microstrip filter are provided, with random errors taken into account. Good correlation between the modeled results and measurements has been demonstrated from this comparison     

A generalized method for the evaluation of mutual coupling in microstrip arrays

An analytical method for the evaluation of mutual coupling in microstrip arrays is discussed. The elements of the array are excited by microstriplines printed on or embedded in the substrate. As an example, the mutual coupling between microstrip dipoles electromagnetically coupled to embedded strip transmission lines is evaluated accurately. The presented method is valid in the millimeter range as weft as at microwave frequencies and does not have any substrate limitations. Also, it accounts for conductor thickness and surface wave excitation. Comparison with experimental results shows excellent agreement.     

Millimeter Wave Scattering of 2-D Frequency Selective Surface by Efficient Method of Lines with Preconditioned CG Technique

In this paper, both banded and symmetric successive overrelaxation (SSOR) preconditioned conjugate gradient (PCG) techniques are combined with method of lines (MOL) to further enhance the computational efficiency of this semi-analytic method. The electromagnetic wave scattering of 2-D frequency-selective surface is used as the examples to describe its implementation, whose analysis usually needs fast algorithms because of electrically large dimension. For arbitrary incident wave, helmholtz equation and boundary condition are used to calculate the impedance matrix and then to obtain reduced current-voltage linear matrix equation in spatial domain. Both banded and effective symmetric successive overrelaxation preconditioned conjugate gradient iterative method are chosen to solve this matrix equation. Our numerical results show that PCG methods can converge to accurate solution in much fewer iteration steps for analysis of the electromagnetic wave scattering from 2-D frequency-selective surface.     

基于激光多普勒效应的液体表面波探测研究

为了对低频液体表面波的频率和振幅进行测量,利用多普勒相干测速的工作原理,提出了一种液体表面散射激光与参考光相干涉的检测方法。对此进行了理论分析,得到了多普勒频移与液体表面波振幅之间的解析关系式,并利用贝塞尔函数分析了频谱分析图中解调出低频液体表面波频率的可行性,设计并实现了一套液体表面波多普勒相干检测的实验装置。结果表明,能够实时准确探测10Hz～40Hz的液体表面波参量,该方法为低频液体表面波的探测提供了新思路。     

Portrayal of the field at the junction between a Yagi structure and a dielectric-rod transmission line

The electromagnetic field of a surface wave crossing the junction between a Yagi structure and a dielectric-rod transmission line is portrayed by the lines of constant field strength and the wavefronts. For matched-field extent, there is negligible reflection and radiation from the junction.     

The structure of high-frequency fields of a surface spin wave in a tangentially magnetized ferrite plate

Vector lines of the high-frequency magnetic field, magnetic induction, and magnetization of a surface spin wave in a tangentially magnetized ferrite plate are calculated. It is found that the magnetic induction vector lines form contrariwise directed curls that are localized near the opposite surfaces of the plate. It is shown that the structure of the magnetic induction of a spin wave and the change of its electric field are interdependent: in the ferrite layer, there is a plane on which the electric field amplitude is zero and which is simultaneously a boundary between the curls of the magnetic induction. It is found out that the directions of the magnetic field and wave magnetic induction vectors are substantially different in the ferrite plate, although these vectors coincide in the half-spaces surrounding the plate.     

外场作用双导线的电磁耦合时域分析方法

基于时域有限差分（finite-difference time-domain，FDTD）法和传输线方程，并结合插值技术，研究了一种高效的时域混合算法，能够快速模拟电磁波照射自由空间和屏蔽腔内双导体传输线的电磁耦合，并实现空间电磁场与双导线瞬态响应的同步计算.该算法先采用FDTD方法模拟双导线周围空间的电磁场分布，结合插值技术构建适用于双导线电磁耦合的传输线方程，再采用FDTD的中心差分格式进行离散，从而求解得到传输线和端接负载上的瞬态响应.同时，分析双导线间距对其电磁耦合的影响，掌握其耦合规律.通过相应数值算例的模拟，并与FDTD方法进行对比，验证了该时域混合算法的正确性和高效性.     

Open Wire Lines

The properties of two-wire lines and single wire lines (surface wave transmission lines) are discussed on a comparative basis. The two-wire line is actually a system of two coupled single wire lines and thus requires a high degree of symmetry to maintain the desired wave mode. While the single wire line is more affected by bends it has the advantages that it is simpler in construction and is less susceptible to weather conditions. The main domain of the two-wire lines lies in the frequency range below 100 mc and that of the single wire line in the range above 100 mc.     

声表面波器件光刻的衍射效应研究

声表面波(SAW)器件光刻过程中,制作的光刻胶线条宽度与掩模版不一致,特别是不同宽度的非均匀线条光刻后线宽变化值存在偏差。该文研究了接近式曝光衍射效应对线宽的影响,分析了掩模版上线条和缝隙宽度、衍射光强、掩模版与光刻胶间距等参数间的关系。结果表明,通过建立光学模型给出了计算曝光后不同线条宽度变化值的方法,采用程序编程可对掩模版数据中不同尺寸的线条和缝隙宽度进行补偿,实现SAW器件非均匀线条宽度的精确控制。     

基于红外激光干涉仪的非球面面形测试技术研究

本文提出了一种基于红外激光干涉仪检测非球面面形的新方法,分为3个步骤:首先,利用红外激光干涉仪测量分析出非球面与标准球面之间的波像差;然后,根据非球面方程得出非球面与标准球面之间波像差的理论值;最后通过计算得出非球面的面形偏差。为验证这一方法的正确性和可靠性,采用ZYGO可见光干涉仪,使用补偿镜法测量了同一块抛物面反射镜的面形误差。结果表明,两种测量方法结果吻合。本新方法方便快捷,具有较强的通用性,可以用于非球面在加工过程中的面形测试。     

Direct observation of electrostatic microfields by four-electron-wave interference using two electron biprisms

A new method has been developed for directly visualizing electromagnetic microfields in real time by the interference of four-electron waves obtained using a transmission electron microscope equipped with a field-emission gun and two electron biprisms. When one object wave and three reference waves interfere, equal-phase lines of the object wave are displayed as the intensity modulation of the interference fringes, in the manner same as in the three-electron-wave interference. The advantage of the four-electron-wave interference is that equal-phase lines are observed without precisely adjusting the angle between the two biprisms or rigorously controlling the fringe spacings of the two biprisms.     

基于小波分解表面波的涂层平板表面缺陷检测方法研究

激光照射在涂层平板表面产生的超声表面波传播时会产生色散现象,该现象会影响表面缺陷检测精度.针对表面波的色散问题,采用有限元仿真分析表面波在涂层平板表面的传播规律,利用Morse小波分解多频表面波信号,提取最大幅值单一频率的缺陷时域信号从而确定表面缺陷位置.在此基础上通过扫描缺陷附近检测点的方式,分析缺陷前沿入射波和缺陷...     

Numerical solution of lossy waveguides: t.l.m. computer program

The transmission-line-matrix method is a time-domain numerical method for solving wave problems. The method uses a mesh of transmission lines to represent a propagation space, and the losses in the space are accounted for by making the transmission lines lossy. Lossy boundaries are simulated by imperfect boundary reflections on the transmission lines. A FORTRAN program implementing this technique is presented.     

端接非线性负载的非均匀传输线瞬态分析

在均匀多导体传输线的时域有限差分法(FDTD)基础上，对非均匀多导体传输线及端接非线性负载的情况进行了分析。结果表明：对于非均匀多导体传输线，采用FDTD法进行瞬态分析极为方便，并且可以处理端接非线性负载的情况；同时，还可获得线上各点的电压、电流波过程。通过实例验证了所提出的FDTD算法的有效性，可用于传输线波过程的研究。     

High-frequency reciprocity based circuit model for the incidence ofelectromagnetic waves on general circuits in layered media

Traditionally a circuit on a high-speed multichip module (MM) or a microwave monolithic integrated circuit (MMIC) is represented in an equivalent circuit by S-parameters for the different components, such as filters or bends, and by transmission lines for the interconnections between the components. Nowadays the S-parameters of the components are easily determined by a numerical electromagnetic analysis. Different components close to each other will interact, often this interaction is unwanted. In the present contribution we develop a circuit model for these interactions without having to perform a global electromagnetic analysis of the interacting components. These interactions are then represented by discrete and distributed sources in the equivalent circuit. Our technique is based on reciprocity and is focused on the surface wave interaction which is often the most important one. Each component is characterized by a surface wave radiation pattern     

Surface Finish Effects on High-Speed Signal Degradation

In high-speed circuits, skin effects and dielectric properties are important factors for signal degradation considerations, especially in the microwave frequency region. When surface finishes are applied to prevent traces from oxidation, the electrical properties of traces are affected. In this work, experimental study and finite element method (FEM) based full wave simulation are used to investigate the effects of hot air solder leveling (HASL) and its alternatives on signal integrity. Classical interconnect structures, microstrip line, and differential mode coupled microstrip lines subjected to different finishes are investigated. Our work reveals that the net conductor loss that results from surface finishes is the dominant factor in signal degradation when the clock frequency is within the microwave frequency region. For microstrip line, the influence of surface finishes on signal distortion is negligible; for differential mode coupled microstrip lines, however, the surface finish effects, especially those with high resistivity, can lead to significant signal distortions. These findings are expected to have strong implications when designing high-speed circuits that meet strict timing requirements.