双各向异性Meta材料矩形波导中的导波模分析

将开口谐振环(SRR)作为加载单元,分析了含有Meta材料矩形波导的新型传输特性.由于SRR所引起的双各向异性效应,横电波将出现传播常数随频率增高而减小的异常TEm0模式以及单模传输频带范围增大的TE0n 模式.特别地,当Meta材料成为单轴双各向异性介质时,横电波和横磁波在此新型介质波导中的相速度能够减慢,甚至达到零速度传播.     

有孔屏蔽腔屏蔽效能的高次模分析

分析了有孔屏蔽腔的屏蔽效能,将传统的等效传输线分析模型扩展为包含TEmn和TMmn高次模的模型,并用该模型分析了缝隙偏离腔体壁中心的情况,得到了实用性较强的一般公式,该公式将腔体内部的高次模和腔体壁的损耗都考虑在内,在一定程度上消除了频率和腔体尺寸对于以往公式的限制.与其他运用传输线高次模分析腔体屏蔽效能的文献不同,本文中TEmn和TMmn的m和n可为任意值,而不需要采用n=0的假设,这更与腔体中的多种模式相符合.     

四脊矩形波导的传输特性

应用有限元分析方法计算了对称四脊矩形波导TE模式的传输特性,即截止波长和场结构图传输特性。分析了传输特性随四脊矩形波导结构尺寸的变化关系曲线,得到脊间距越小,相对的截止波长越大。四脊矩形波导中主模的截止波长可随脊宽的变化而变化,在脊间距d/b一定的情况下,截止波长在s/a=0.4时比在其他尺寸时大。这些结果和计算数据将为四脊矩形波导器件的小型化提供指导。     

用横向谐振微扰法分析非理想波导的损耗特性

分析非理想波导的损耗特性是微波工程中很重要的实际问题之一,对它的精确求解往往和波导元件及微波系统性能的分析紧密相关。根据横向谐振原理和微扰理论,本文提出了一种分析非理想波导损耗特性的新方法,推导出了一组计算矩形波导TEm0和TE0n模导体损耗的衰减常数公式,并分析计算了矩形波导的损耗特性。通过对几种本征模式的计算,证实了本文方法的正确性和有效性。这种横向谐振微扰法具有原理简单、表达直观、计算简便易行等优点,可以更便捷地应用于解决实际微波工程问题。     

非共晶Au/Ge欧姆接触工艺改善扩散法n沟道GaAs MESFET

用非共晶组份Au/Ge合金做n型GaAs欧姆接触.系统测定了不同Au,Ge厚度做欧姆接触的比接触电阻值.以150A|°Ge/2000—2500A|°Au的配比,在400℃,10min(实际是3min)下合金化,其比接触电阻值能与文献报道的数据相比较,且表面很平.这有利于栅长≤1μm场效应管的光刻,且能改进器件性能与成品率.用作在高阻衬底上以扩散法制备n沟道场效应管的欧姆接触,改进的器件性能在栅长是1.2μm,栅宽150μm时,跨导8m达29m3.另一个样品在栅长1.3μm,栅宽300μm时,fmax=21GHz,在4GHz下,噪声系数N_F≤1.5dB,相关增益Gα为11dB.     

JFET压磁电效应的理论分析

本文用标准的松弛方法研究了结型场效应晶体管的压磁电效应。利用准平面拉普拉斯方程及有限差分法计算了不同栅电压、漏电压以及n沟道硅器件不同宽长比的压力灵敏度和磁灵敏度。在P0,B=0,器件宽长比为W/L=1/2-1时,电流性压力灵敏度约为:2.5％cm2/N。据此,提出了一种有良好工作稳定性及噪声性能的力学量敏感器件结型场效应力敏管(Junction field effect-pressure sensor)。     

毫米波段波导传输的一些问题

1.引言微波技术不断地在向更短的波段发展。缩短波长使我们有可能使用更宽的频带和更多的通路。一般的波导传输系统只采用一个波型(通常是主波)的传输;在这种系统中,波导的尺寸和半波长相近,因此,除了主波以外,高阶波型都是消失波。但是,当使用更短的波段(毫米波段)时,通常采用的波导尺寸就比半波长大得多,因此,波导所能传输的波型(非消失波)就不只是一个,而是许多个。非消失波的数目决定于波导尺寸和波长的比例。     

太赫兹过模传输线损耗研究

太赫兹波的频率较高,在波导传输中损耗较大。本文采用微扰法对太赫兹波在矩形波导和圆波导中传输时的损耗进行了理论分析,并对矩形波导与圆波导中不同频率,不同尺寸以及不同模式的衰减特性进行了比较,结果表明采用圆波导TEo。模传输可获得最小的衰减。     

阶梯加载矩形波导栅慢波系统的研究

提出了一种新型的毫米波行波管慢波结构———阶梯加载矩形波导栅慢波系统.考虑槽区内场的高次项,利用各阶梯相邻面的阶跃条件以及互作用区和加载区的场匹配条件,获得了该结构的色散方程,并导出耦合阻抗.讨论了主模在其中的传播情况,并分析了系统结构参数变化对慢波电路高频特性的影响.数值计算表明加载阶梯的尺寸对此结构内波的传播特性有很大影响,可以根据不同的要求来选取具体设计参数.该结果为进一步研究和设计此类行波管高频系统提供了理论基础.     

两种环栅MOS管的等效宽长比分析研究

对抗总剂量辐射加固中常用的两种环栅MOS管的等效宽长比进行了研究。对b字形环栅管的宽长比计算模型进行验证,发现b字形环栅结构无法实现小宽长比。分别在0.35 μm和0.18 μm工艺下进行流片测试,发现该计算模型的准确性较低,测试样品的宽长比最大偏差超过30%。针对b字形环栅结构的缺点,设计了8字形环栅结构,可实现小宽长比管和倒比管,宽长比的值易于预估,且几何尺寸与直栅结构相近。在0.18 μm工艺下进行流片验证。测试结果表明,8字形环栅管的饱和电流偏差值均在6%以内,宽长比预估值的准确性较高,能够非常方便地被应用于实际设计中。     

Full-wave analysis of waveguide-to-microstrip transitions for millimeter wave applications

A “full-wave” solution is presented for the waveguide to microstrip transition. The exact Green's function of the transition is used in a moment method procedure. The behavior of the microstrip transition to a rectangular waveguide is studied with respect to the critical dimensions of the microstrip width, length and backshort location. The convergence characteristics of the full wave analysis method are investigated, along with the current distribution and the input impedance. Results given for the return loss is compared with measurements.     

Plasma travelling wave antenna

The possibility of using plasma column as linear travelling wave antenna is studied. It is shown that surface current waves propagating in plasma column of finite length are a source of paraxial electromagnetic radiation of decimeter band. Influence of dielectric waveguide, which surrounds cold isotropic plasma, on dispersion properties of plasma column is investigated. The corresponding dispersion equation for eigenwaves of circular dielectric waveguide filled with plasma is derived and solved numerically. Plasma and waveguide parameters are determined under which the surface wave slowing-down is close to unity leading to antenna’s radiation primarily in axial direction. It is shown that in case of plasma density around 10¹²−10¹³ cm⁻³ dispersion of the considered wave is close to dispersion of waves propagating in metal travelling wave antenna.     

矩形缺陷光子晶体太赫兹波波导的慢波特性

设计了一种工作于太赫兹波段的矩形孔缺陷光子晶体慢波波导。首先分析三角空气孔型光子晶体的带隙特性,引入线缺陷形成波导,并将邻近缺陷空气孔设为矩形,通过分析矩形孔尺寸对波导的带隙结构、群速度的影响,确定孔尺寸;研究缺陷宽度对缺陷模式的影响,并通过优化将缺陷模式频率移到目标频率338 GHz处,最终在布里渊边界处实现了c0/1543(c0=3×108m/s)的低群速度,证明了矩形缺陷光子晶体太赫兹波导良好的慢波特性。     

Method for measuring the attenuation and phase constants of asurface wave propagating along an infinite plane

A method is presented for determining the attenuation and phase constants of a surface wave propagating along an infinite planar layer of metal-backed material. Two input impedance measurements of a rectangular waveguide partially filled with the test material are used to infer the propagation characteristics of the plane surface wave. Measurements are presented which validate the method     

The Paradoxical Surface Wave (Crack Wave) in Ferrite-Filled Waveguides

Existing theories that relate to propagation in a rectangular waveguide loaded with a transversely magnetized slab of ferrite are reviewed and new points brought out. In the loss-free case, in which the ferrite stab lies against one of the waveguide walls, conflicting results are obtained. If the width of the air gap between the ferrite slab and the waveguide wall is set equal to zero, a single surface wave propagating in one direction only is predicted. This result leads to a thermodynamic paradox. If, however, the air gap is assumed infinitely small but different from zero, two surface wave modes, which transport energy in opposite directions, are predicted. The aim of this paper is to establish whether or not a surface wave exists when there is no air gap for a real structure which is not free of loss. The experimental results show conclusively that the surface wave is present. It is concluded that a mathematical model is required, which assumes losses. If for reasons of simplicity a lossless model is used, then it must be assumed that the width of the air gap is never identical to zero. The structure selected for the experimental work consisted of a rectangular block of ferrite that completely filled the cross section of an X-band waveguide.     

二氧化钛光子晶体波导的太赫兹波传输特性

本文应用时域有限差分法研究了二维二氧化钛光 子晶体波导的禁带范围和太赫兹波的 传输特性,分别设计了带隙宽度为0.226 THz 、0.2728 THz和0.316 THz的直线型、直角型和T 型二氧化钛光子晶体波导结构。研究发现,相比传统波导,本文设计的二维二氧化钛光子晶 体波导不仅在直线路径中有较高的太赫兹波传输效率,而且在转角的路径中也有很高的太赫 兹波传输效率。此研究结果为太赫兹器件的设计和制作提供重要理论依据,为高速宽带无线 通信系统的发展提供重要理论借鉴。     

Finite-element analysis of magnetostatic wave propagation in a YIGfilm of finite dimensions

A unified numerical approach based on the finite-element method is described for the magnetostatic wave propagation in a YIG film of finite dimensions. Both magnetostatic surface wave modes are treated. The validity of the method is confirmed by calculating the magnetostatic wave modes in a YIG-loaded rectangular waveguide and in a YIG film of finite width. The numerical results of a YIG films with nonuniform bias field along the film width are also presented, and the effects of bias field distributions on the delay characteristics and potential profiles are examined     

Guided-Wave Experiments with Dielectric Waveguides Having Finite Periodic Corrugation

A planar dielectric waveguide having finite periodic rectangular corrugation is investigated analytically and experimentally, in case of surface waves propagating at an angle to the corrugation. In analytical considerations, a finitely corrugated guide is regarded as consisting of many step discontinuities connected by a length of uniform slab waveguide, and its propagation characteristics in the Bragg interaction region are derived from a cascaded connection of the transmission matrix expressing a step discontinuity. Although the present method takes only surface wave modes into account and neglects the wave with continuous spectrum, the calculated results show an excellent agreement with experimental ones which are performed for art H-guide in the microwave region.     

H-plane Bends in Overmoded Rectangular Waveguide Systems†

The eigenvalue and eigenfunction of the fundamental wave propagating in an ff-plane bend of rectangular cross-section is solved approximately by means of a perturbation method. In an oversize system,H⁰¹-mode power is found to be most strongly coupled to the H⁰²-mode which is assumed to be propagating. This mode coupling can be greatly reduced within a limited band width by offsetting laterally, in the H -plane of the H⁰¹-mode, the adjacent straight waveguide sections. Theoretical study and experimental verification for such a system are given.