Propagating Modes Along a Thin Wire Located Above a Grounded Dielectric Slab

The possible propagating modes supported by a wire located parallel to a grounded dielectric slab are investigated. While at low frequencies, a "quasi-TEM" behavior is exhibited, it is shown numerically that under certain conditions, a very different "surface-attached" character emerges. These results suggest the possibility of similar behavior occurring in the related, but more difficult to analyze configuration of open microstrip lines. The particular structure we analyze here is of interest mainly because of its potential application in air strip ground RADAR monitoring systems, which conceivably can consist of a horizontal wire located above a reinforced concrete slab lying above a conducting earth surface.     

Analysis of Radiation From a Line Source in a Grounded Dielectric Slab Covered by a Metal Strip Grating

In this paper, we present a study of the radiation from a line source located inside a grounded dielectric slab covered by a metal strip grating. The array scanning method was applied to enable an efficient “unit cell” formulation. The numerical solution was obtained with the use of the spectral method of moments. Both TM and TE cases were solved. The effects of the geometrical parameters on the propagation of guided modes and their excitation are studied.      

Scattering from a Periodic Array of Double-Dipole Elements over a Grounded Dielectric Slab

An analysis method of electromagnetic scattering from periodic patch array of double-dipole elements on a grounded dielectric substrate in case of oblique incident and arbitrary polarization is considered. The basis functions are chosen to be entire cosinusoidal functions covering the rectangular shaped domain in which the original dipoles are inscribed, unlike the conventional method in which basis functions are defined only for the conducting element region. To confirm the validity of the proposed analysis method, we calculate the normalized scattered power for two propagating modes and compare the results with those obtained by the previous numerical method for the double dipole elements of rectangular type and parallelogram type which have the property of frequency scanned reflection and polarizer. Good correspondence has been observed between them. Some numerical results such as variation of power and axial ratio of first-order diffracted wave by a periodic array of double-dipole elements are compared with previous results.     

Radiation of Millimeter Waves from a Leaky Dielectric Waveguide with a Light-Induced Grating Layer

A theoretical analysis is presented for the radiation characteristics of millimeter waves in a periodic dielectric waveguide having a light-induced grating layer. The waveguide is assumed to be composed of an insulator (sapphire) slab whose one surface is coated with a high-resistivity semiconductor (silicon) film. A boundary-integral-equation formulation is employed to obtain characteristic solutions of the waveguide. Numerical calculations are made at 94 GHz for both TM and TE polarizations. Estimations of the illumination power required to produce the grating are given. The waveguide presented in this paper, in conjunction with a high-power semiconductor diode laser array as a light source, may be developed to operate as an electronically beam-steerable leaky-wave antenna at millimeter-wave frequencies.     

On the Propagation of Leaky Waves in a Longitudinally Slotted Rectangular Waveguide

The field theory approach is used to study leaky-wave propagation in a rectangular waveguide with long nonresonant slots in the narrow walls. Radiation from the slots is confined by parallel plates which act as transmission lines guiding the energy away from the slots. The complex dispersion equations for TE waves are examined and solved using an iterative numerical technique. Propagation characteristics both in the axial and transverse directions are presented, along with the electric field distribution and power flow. Restrictions on the analysis and on the power-handling capacity imposed by slot width also are described. Measurements of the phase characteristics of the dominant mode are in good agreement with theoretical values.     

Even-Odd Modes of a New Transmission Line Based on Semi-Open Dielectric Slab

An original transmission line based on a planar waveguide splitter with central magnetic-dielectric filling is considered. A rigorous electrodynamics model is presented for calculating propagation parameters of hybrid even-odd eigenmodes. It was determined that the physics of the wave processes of the line for these modes is identical to the physics of open structures, though the structure geometry has semi-open character. Numerical experiments prove that new line is very promising for different millimeter wave applications, such as antennae and three-dimensional integrated circuits (TDIC).     

Rigorous Analysis of the Scattering of Surface Waves in an Abruptly Ended Slab Dielectric Waveguide

The reflection and the scattering properties of even TE and TM surface waves incident in an abruptly ended dielectric slab waveguide are analyzed. The discontinuity is regarded as a junction between two open waveguides namely the dielectric slab waveguide and the free space waveguide. The boundary conditions acting together with the orthogonality provide singular coupled integral equations on the discrete and the continuous wave amplitudes at the discontinuity. These singular coupled intergral equations with Cauchy kernels and infinite limits of integration are solved by iteration via the Neuman series. Numerical results are presented for the reflectivity of the even TE/sub 0/ and TM/sub 0/ fundamental modes, together with their mode conversion on even TE/sub 2/ and TM/sub 2/ in a slab where two guided modes can propagate. Reflectivity and mode conversion of higher order excitations are also investigated     

Excitation of Plasma Waves in an Unbounded Homogeneous Plasma by a Line Source

The radiation characteristics of a line source of magnetic current embedded in a homogeneous electron plasma of infinite extent are investigated for the case in which a uniform magnetic field is impressed externally throughout the medium in the direction of the source. The single-fluid theory of magnetohydrodynamics is employed. A very simple model is assumed for the plasma. Under this assumption, it is found that there are two modes of propagation of waves of small amplitude. By examining the behavior of these modes in the limiting cases of vanishing external magnetic field or infinite source frequency, they are identifiable as the modified forms of the usual plasma and optical modes which exist in an isotropic electron plasma. The dispersion relations for these two modes are discussed. The power radiated in each of the two modes is also evaluated. It is found that the power radiated in the optical mode is always lower than that due to the line source in free space, whereas the power radiated in the plasma mode is higher than that value for certain ranges of the source frequency.     

Characteristic Impedance of the Slab Line with an Anisotropic Dielectric (Short Papers)

The characteristic impedance of the slab line with a circular conductor having an anisotropic dielectric is presented by rising the affine and conformal transformations. Moreover, a simpler approximate formula of the impedance expressed in term of epsilon /spl par/, epsilon /spl perp/, and r/h is also presented, where epsilon /spl par/, epsilon /spl perp/ r, and h, are the principal axes-relative dielectric constants of the anisotropic dielectric, the inner conductor radius, and the half Iength between ground planes, respectively.     

漏波和高次谐波的耦合模式模型公式的严格推导

表面波理论中,广泛采用耦合模式(COM)模型来描述指间多次反射效应.现有COM模型是建立在一个简化基础模型上的,其简化包括1)耦合反射系数k和换能系数a均假定为常数以保证偏微分方程有解,而实际上它们是空间位置的函数;2)传播常数k假设为实数,但对漏表面波,k应为复数.为此,本文严格推导了COM理论公式,得到了耦合反射系数的谐波级数展开,由此可以重建指条反射系数的空间分布,同时将周期栅格阵下的COM方程推广到波传播有体波泄漏的情况,即包括漏波和Rayleigh波高次谐波的情形.最后给出一个实例,对一种单向单相换能器的基本单元计算了其耦合反射系数和换能系数,该结果证实了本文的推导.     

On the Design of Transitions Between a Metal and Inverted Strip Dielectric Waveguide for Millimeter Waves

The results of a study of three types of transitions between the rectangular metal waveguide and the inverted strip guide are reported. Reflected power measurements from each type of transition and insertion-loss measurements for configurations involving the three transitions have also been carried out. The procedure of determining the optimum parameters for the transition is quite general, and has the potential for being extended to other dielectric structures.     

隔离线接地孔间距对抑制串扰效能影响的分析

抑制印制电路板上微带线间串扰是高速PCB 信号完整性设计的重要内容。文中研究了在两平行微带线之间加上带有接地孔的隔离线这种方法减小串扰的有效性,讨论了在工作频带内因此发生谐振的孔间距要求,仿真得到了不同情况下的S 参数、电流分布图。通过加上升时间0.1ns、周期1ns 的方波脉冲激励,比较了改善前后端口的串扰的情况,可以看出串扰得到了有效地抑制。     

Errors in Dielectric Measurements Due to a Sample Insertion Hole in a Cavity

The measurement of complex permittivities of isotropic media at microwave frequencies is performed with high precision by means of cylindrical cavity resonators. However, a hole in the cavity wall, for inserting the sample causes a frequency pulling of the resonator, which in turn introduces an error in the measured dielectric constant. These effects are measured, and with perturbation theory as a guide, correction factors are developed.     

Propagation of Waves through Magnetoplasrna Slab Within a Parallel-Plate Guide

By applying the variational equation is established for handling wave reaction theory, a variational propagation in a parallel-plate guide within which a magnetized inhomogeneous lossy plasma slab is inserted. The equation is then solved by the finite-element method along with the frontal solution algorithm. With such an approach, the reflection coefficient and the field distribution in the slab are obtained. In this study, the factors which may influence the propagation characteristics of the guide are studied. These factors include the plasma electron density, the strength and the direction of the static magnetic field, the width and the thickness of the slab, and the electron collision Iosses. A special modal expansion solution is also incorporated to investigate an anomalous numerical instability associated with the present numerical algorithm.     

On the Existence of Transverse Acoustoelectric Stoneley Waves and Their Applicability in Acoustonanoelectronics

The Stoneley problem is analytically solved for the piezoheterolayers of cubic symmetry crystals for the first time. New types of acoustoelectric waves, in contrast to classical Stoneley waves, are plane-polarized in the direction orthogonal to the sagittal plane. The wave electric field in each layer is elliptically polarized in the sagittal plane. The use of new types of acoustoelectric waves will make it possible to significantly extend the capability of modern acoustoelectronic devices and is directly associated with the transition from acoustoelectronics to acoustonanoelectronics corresponding to the nanometer wavelength range with a carrier frequency of the order of hundreds of gigahertz.     

Analysis of a TEM Cell with Septum on a Dielectric Slab

A quasi-TEM approach based on conformal transformation is used for the determination of the characteristic impedance of a rectangular coaxial line (TEM cell) having a symmetrically located inner conductor (septum) supported on a dielectric slab of equal width. The method of determination of the capacitance of the dielectric-filled portion is discussed. The results on characteristic impedance for two values of dielectric constant are presented.     

Properties of Near and Far Fields for the Electric Line Source Illumination of a Lossy Metamaterial Covered Dielectric Cylinder

The electric field properties of the electric line source radiation in the presence of a lossy metamaterial covered dielectric cylinder are investigated. Firstly, the electromagnetic model configuration is given. The exact solution of the electromagnetic is presented. Secondly, the near field and the far field properties are investigated according to the electromagnetic and geometrical parameters. The different “focus” phenomenon, the directivities and the normalized radiation resistance are discussed and important conclusions are obtained. During all the numerical computation, the lossy conventional material covered dielectric cylinder is utilized as the reference.     

Nondestructive Measurement of a Dielectric Layer Using Surface Electromagnetic Waves

In this investigation, the possibility of nondestructively measuring the thickness and dielectric constant of a layer of dielectric material on a conducting substrate by surface electromagnetic waves (SEW) has been demonstrated. The theoretical approximate dispersion relations near cutoff were derived for both the TE and TM modes and found to be linear functions of frequency, the thickness and dielectric constant were then calculated as simple algebraic functions of the slope and intercept of the dispersion curve. An experimental apparatus utilizing a prism-coupler was constructed to excite surface electromagnetic waves in a dielectric layer whose characteristics were known. By suitable measurements of the frequency and the coupling angle of the source, the dispersion curve was determined experimentally and the resulting dielectric constant and thickness of the layer calculated.     

Input Admittance of a Circular Waveguide Aperture Covered by a Dielectric Slab

The input admittance of a circular waveguide opening onto an infinite flange with a homogeneous lossy dielectric coating is derived using integral transforms and assuming the dominant TE11mode as the trial field at the aperture. Admittance calculations for low-loss dielectric sheets of various thicknesses are given and compared with measurements obtained using ground planes of varying sizes. Excellent agreement with theory is obtained for the circular waveguide terminated into a square ground plane only1lambdato2lambda. on a side. A quantitative comparison of the surface wave contribution to the total admittance is also given.     

Analysis of Radiation Phenomena in a Wedge Ended Dielectric Slab Waveguide

Radiation phenomena observed in a wedge shape ended dielectric slab waveguide are analyzed using mode matching technique. The case of transverse electric polarization (TE) being parallel to dielectric slab waveguide is assumed. In order to describe the fields in the wedge region, a stack of dielectric plates is assumed and in each layer the fields are expanded in terms of the mixed spectrum of guided and radiated modes. A similar expansion is used in the constant thickness slab waveguide while in free space medium a continuous-radiation mode expansion is used. Then a mode matching approach is applied, incorporating the orthogonality properties of mixed spectrum modes, in order to compute the wave fields inside the dielectric slab waveguide and wedge medium. Mode matching is achieved by discretizing the continuous radiation mode spectrum leading into a numerically stable solution provided a sufficient large number of points are used to convert integrals into finite summations. Numerical computations are carried out for various wedge geometries and shapes including linear and exponential profiles.