A Study of Multielement Transmission Lines

Although many papers have been published on the subject of multielement transmission lines, the application to practical problems seems rather inconvenient. The author proposes a solution to the general equations which relate the voltage difference between the lines and the mesh current. Under particular conditions, it is shown that only a single type of propagating mode exists. In this case, the solution has been obtained by the so called "decomposition method", i.e., assuming several virtual two element transmission lines in lieu of the existing multielement transmission line. The problem has been solved by means of the resolved superposed virtual lines taking into account the existing boundary condition.     

计算周期性导波结构的时域有限差分方法

本文提出一种计算周期性导波结构的时域有限差分方法.由Floquet定理建立边界条件,在电场边界和磁场边界上两次使用Floquet定理,从而将计算域限制在一个周期结构内,并且在导波结构侧面引入吸收边界条件,保证了计算精度.通过预先给出传播常数,经FDTD迭代计算,其谐振频率就是该传播常数所对应的工作频率.     

Impact of a normally conducting surface layer on attenuation inhigh-Tc superconducting microstrip transmission lines

A two-dimensional (2-D) model is adopted to characterize high-T _c superconducting (HTS) microstrip transmission lines with a normally conducting surface layer. The model is verified by comparison with a full-wave analysis calculation for identical all-superconducting lines and by calculation of the current distribution and propagation properties for a normal conductor version of the microstrip. Estimates are obtained for the transmission line attenuation constant versus thickness and conductivity of the resistive surface layer. The results suggest that in situ deposition of a normal metal overlayer on the HTS film surface may be a viable technique to secure the long-term performance of microwave devices     

Quasi-TEM Analysis of "Slow-Wave" Mode Propagation on Coplanar Microstructure MIS Transmission Lines

We present a simple quasi-TEM analysis of "slow-wave" mode propagation on micron-size coplanar MIS transmission lines on heavily doped semiconductors and compare theoretical results with measurements on four such structures at frequencies from 1.0 to 12.4 GHz. Excellent agreement is found, which shows that the "slow-wave" mode propagating on these transmission lines is, in fact, a quasi-TEM mode. Relatively low-loss propagation along with significant wavelength reduction is observed. Conduction losses of the metal, which have been tacitly ignored in previously published "full-wave" treatments of "slow-wave" mode propagation, are included in the theory and are shown to dominate the attenuation at frequencies below 25 GHz and to still be significant at frequencies up to at least 100 GHz.     

Electromagnetic Wave Propagation in Twisted Anisotropic Media

The complete solution of the differential equation describing the propagation of plane uniform TEM waves along the twist axis of a twisted anisotropic medium with a constant rate of twist is shown to be of exponential type, consisting of two identical pairs of independent propagation modes, each pair being associated with a particular direction of energy flow. Knowledge of the complete solution is used to solve the boundary value problem relative to wave penetration into a twisted medium at normal incidence, a numerical example being given illustrating the polarization transformation properties of the medium near the short wavelength limit. Analysis of mode properties reveals circnlar birefringence should occur in twisted media at long wavelengths. A link power, as shown by certain crystalline substances provided by the theory.     

Fourier Transformed Finding Propagation Matrix Method of Characteristics of Complex Anisotropic Layered Media .

A planar structure having arbitrarily located conductor lines immersed in complex anisotropic media presents one with a very general guided wave problem. This problem is solved here by a rigorous formulation technique characterizing each layer by a 6 x 6 tensor and finding the appropriate Fourier transformed Green's function matrix G of 2n x 2n size. From G, a method-of-moments solution for the propagation characteristics follows, including propagation constant eigenvalues and field eigenvectors at all spatial Iocations. The method is very versatile and can handle a huge class of microwave or millimeter-wave integrated circuit or monolithic circuit problems, no matter how simple or complex as long as they possess planar symmetry.     

一维不均匀介质中波传播瞬态响应的传输线模型分析

提出了用传输线模型分析一维不均匀介质中波传播的瞬态响应。这种方法将一维不均匀介质用多层介质近似，并进一步用级联的传输线模型等效。分析的过程是：首先对局限在某一时间段内的输入电磁信号进行傅里叶变换得出其频谱，然后研究该频谱的主要分量在所研究介质中的传播，并得出波传播方向任一截面上瞬态信号的频谱，最后通过快速傅里叶变换得出时域瞬态响应。这种方法适用范围广，数值计算方便，只要离散时间间隔足够小，抽样点数足够大，就能达到一定的精度。     

Eigenmodes of a 2D array of coupled slot lines in the impedance approximation

A 2D periodic array of coupled slot transmission lines is considered in the approximation of equivalent boundary conditions. The eigenmode problem for an array operating in the quasi-periodic mode is formulated and solved. The dispersion equation for eigenmode propagation constants and expressions for eigenmode fields are obtained. The behavior of eigenmodes in a frequency band and in a range of values of geometric parameters is analyzed. The orthogonality of eigenmodes is shown. Theoretical results are compared to the results of numerical calculation performed with the use of electromagnetic simulation systems.     

Electromagnetic coupling between wires inside a rectangular cavityusing multiple-mode-analogous-transmission-line circuit theory

This paper examines the coupling between two arbitrarily positioned wire segments inside a rectangular enclosure. The enclosure is treated as a superposition of analogous transmission lines which have been short circuited at two positions on the propagation axis. Each analogous transmission line is associated with a particular waveguide mode in the cavity. Previous work has used this analogy to predict the coupling between two monopoles inside a small box using the dominant TE ₁₀ mode. This paper considers the general case of high-frequency coupling between two wire monopoles in a large rectangular cavity, where several higher order modes are active. By taking into account higher order modes, and the mutual coupling between the modes, a simple equivalent circuit is presented which can give a prediction for the coupling between the monopoles. Experimental results for various monopole pair positions are shown, which indicate the success of the multimode theory. The technique requires far less computer resources than traditional methods for solving such a problem (e.g., MoM, TLM or FDTD), with solution times of less than a second on an average PC. In addition, considerable insight into the coupling process can be gained by including or excluding particular waveguide modes. This is not possible with numerical methods     

Capacity and Characteristic Impedance of Strip Transmission Lines with Rectangular Inner Conductors

An example of the rigorous solution of a complex region boundary value problem is presented. The particular problem, the electrostatic capacity and characteristic impedance of a strip transmission line, is solved exactly and numerical results are given for a particular geometrical configuration.     

Generalized spectral analysis of planar lines on layered mediaincluding uniaxial and biaxial dielectric substrates

The spectral-domain analysis is generalized to compute the dispersive properties of a wide variety of planar and quasiplanar transmission lines (microstrips and finlines) printed on a stratified dielectric medium. Uniaxial and biaxial dielectric anisotropy can be easily manipulated due to the definition of a transverse propagation matrix characterizing each dielectric layer. The whole boundary value problem is reduced to two simpler problems involving only one or two dielectrics, and the spectral dyadic Green's function is derived by a recurrence algorithm. The dispersion equation is derived by using the Ritz-Galerkin method. The numerical convergence is substantially improved taking into account the asymptotic behavior of the series. A number of illustrative examples are included to emphasize the power of the method     

Interconnect energy dissipation in high-speed ULSI circuits

This paper presents a detailed empirical study and analytical derivation of voltage waveform and energy dissipation of global lines driven by CMOS drivers. It is shown that at high clock frequencies where the output voltage at the termination point of the transmission line may not reach its steady-state value during the clock period, it is possible to reduce energy dissipation while meeting a dc noise margin by driver sizing. This is in sharp contrast with the steady-state analysis, which states that driver size has no impact on the energy dissipation per output change. In addition, we propose a new design metric which is the product of energy, delay and some measure of ringing in lossy transmission lines. In particular, this paper provides closed-form expressions for the energy dissipation, 50% propagation delay, and the percentage of maximum undershoot when the circuit exhibits an underdamped behavior. This metric is used during the driver sizing problem formulation for minimum energy-delay-ringing product. The experimental results carried out by HSPICE simulation verify the accuracy of our models.     

Identification of propagation regimes on integrated microstriptransmission lines

There has been a resurgence of interest in the propagation characteristics of open integrated microstrip transmission lines. This is due in part to the discovery of diverse propagation regimes for higher-order modes on open lines. In contrast to the dominant EH₀ mode, three distinct propagation regimes exist for higher-order modes on microstrip transmission lines. In this paper, a rigorous spectral-domain integral equation formulation is used to analyze propagation in all three regimes. This formulation provides a clear physical picture of the different propagation regimes based on the mathematical location of poles and branch points in the complex spectral-variable plane. As an illustration, the formulation is applied to the case of an isolated uniform microstrip transmission line. The integral equation is discretized via the method of moments, and entire-domain basis functions incorporating suitable edge behavior are utilized to provide convergence with relatively few terms. The results obtained are compared to the results of other workers, and good agreement is observed     

Frequency-selective reflection and transmission by a periodicdielectric layer

The feasibility of using a periodic dielectric layer, composed of alternating bars having dielectric constants ϵ₁ and ϵ₂, as a dichroic surface at millimeter-wave frequencies is examined. For oblique incidence, it is found that total transmission and total reflection can be obtained at different frequencies for proper choices of ϵ₁ and ϵ₂ and the geometric parameters. The frequencies of total reflection and transmission can be estimated from wave phenomena occurring in a layer of uniform dielectric constant equal to the average value in the periodic layers. For some of the frequencies of total transmission, the bandwidth for 90% transmission is found to be 40%. The bandwidth for 90% reflection is always found to be much narrower, the greatest value obtained being 2.5%     

Diffraction by a compact obstacle near an open end of a planar dielectric waveguide

The modified discrete source method is applied to consider the 2D problem of diffraction of the mode of a semi-infinite planar waveguide (layer) by a dielectric body located near the boundary of the waveguide end. The problem is solved under the condition that the refraction coefficients of the media in the interior and exterior of the dielectric layer have close values. A system of integral equations is derived. The dependences of the reflection coefficient on the coordinates of the body and the angular dependences of the scattering pattern are obtained for various geometries of the scatterer.     

Numerical solution of Green's function of potential field ofeccentric point source in axisymmetric inhomogeneous media

An analysis has been performed for a borehole direct-current resistivity boundary value problem in axisymmetric inhomogeneous media. In order to solve the problem of eccentric excitative sources in actual electrical logging, the authors apply an efficient numerical mode matching (NMM) theory to present Green's function of the potential field of an eccentric point source. The basic and higher order modes are described by applying numerical eigenmode expansion, and the local reflection and transmission matrices are used to match the boundary condition of potential field on every planar layer. Some typical examples are calculated and analyzed. The first example is concerned with a 16-in normal tool, which results are in excellent agreement with the data published previously in references. The second example about the micro laterolog-3 point electrodes is calculated to display a range of different eccentric effects. Some interesting and useful results are obtained     

Oversize Waveguide Directional Coupler (Correspondence)

Oversize rectangular waveguide using TE/sub 10/ mode propagation has been suggested as a means of reducing the attenuation and fabrication difficulties of transmission lines and components for frequencies above 40 Gc. Experiments on straight sections of such transmission lines show that it is superior to pure optical transmission for short distances.     

部分手征介质填充同轴线的反射和透射特性

用多模网络与严格模匹配相结合的方法 ,对部分手征介质填充同轴线的反射和透射特性进行了分析和求解 .对横截面采用等效径向传输线 ,对纵向采用多模传输线方法 ,并且利用结构的对称性使得问题简化 .讨论了不同情形下手征参数和介电常数对反射和透射特性的影响 .     

Surface Plasmon Amplification in Planar Metal Films

The propagation and amplification of surface plasmon polaritons (SPPs) is studied at the interfaces between metals and active media. A permittivity renormalization technique is proposed and developed to obtain an explicit analytic expression for the critical gain required to achieve infinite SPP propagation length. A specific multiple quantum-well (MQW) system is identified as a prospective medium for demonstrating efficient SPP amplification at telecommunication frequencies. The proposed system may have a strong impact on a variety of photonic devices ranging from plasmonic nanocircuits, subwavelength transmission lines and plasmonic cavities to nanosized transducers.     

三维PML吸收边界条件在微带线不连续性问题分析中的应用

将完全匹配层（PML）吸收边界条件从求解二维TE／TM模问题推广到求解三维混合模传输线问题,通过对各种三维微带线不连续性结构散射特性的计算表明,文中给出的电磁PML吸收边界条件保持了二维情况下宽带、高精度的优点,在复杂结构的FDTD分析中具有重要的实用意义。