On excitation of waves over a plane surface of a highly conductive medium,the Zenneck wave

Effective excitation of a surface wave, in particular, the Zenneck wave, over a plane boundary of a highly conductive medium is considered.     

On Slow and Fast Surface Waves Propagating on Plane Boundaries of Conducting Media with High Conductance. The Zenneck Wave

The regularities of transition of phase and group velocities from slow surface waves (whose velocities are below the light speed) to fast surface waves (whose velocities are above the light speed) on the plane boundaries of highly conducting media are investigated when the parameters of media vary. It is shown that the structure of waves does not change qualitatively in the case of this transition: the waves remain to be surface ones in contrast to surface waves of dielectric waveguides. The latter ones are transformed into leaking waves or their structure changes in a more complicated way in the case of such transition. A result relating, in particular, to the Zenneck wave is obtained.     

Surface Wave Radiation from a Thick, Semi-Infinite Plane with a Reactive Surface

The idealized surface wave radiator considered here is a thick, semi-infinite plane with a reactive surface. The scattered field is found when symmetrical and unsymmetrical surface waves are radiated at the termination of the plane. Since there are semi-infinite boundary conditions, the Wiener-Hopf technique is used for finding equations describing the scattered field. These equations contain a series of unknown constants which require numerical solution. Field patterns are plotted for different plane thicknesses and surface reactances with even excitation. The scattering of a plane wave by a thick, reactive plane is also discussed briefly.     

Surface waves on a lossy planar ferrite slab

The parallel-polarized surface waves which propagate on a planar ferrite slab are considered. The ferrite material is isotropic and homogeneous, the slab rests on a perfectly conducting ground plane, and the ambient medium is free space. Only one mode can propagate on a thin lossless slab, but more and more of the higher order modes begin to propagate when one increases the thickness or the loss tangent of the slab. As the thickness and the loss are increased, the lowest order mode takes on the properties of the Zenneck wave. At the same time, the higher order modes take on the properties of a homogeneous plane wave propagating in the grazing direction in the slab. Among the most interesting properties of a surface wave are the attenuation constant and the phase velocity. Contour maps are included to show how these quantities depend on the thickness, permittivity, permeability and loss tangents of the ferrite slab. Additional insight is provided by graphs showing the root trajectories, cutoff boundaries and field distributions of the four lowest order surface-wave modes.     

Surface Current Density Mapping for Identification of Gastric Slow Wave Propagation

The magnetogastrogram (MGG) records clinically relevant parameters of the electrical slow wave of the stomach noninvasively. Besides slow wave frequency, gastric slow wave propagation velocity is a potentially useful clinical indicator of the state of health of gastric tissue, but it is a difficult parameter to determine from noninvasive bioelectric or biomagnetic measurements. We present a method for computing the surface current density from multichannel MGG recordings that allows computation of the propagation velocity of the gastric slow wave. A moving dipole source model with hypothetical as well as realistic biomagnetometer parameters demonstrates that while a relatively sparse array of magnetometer sensors is sufficient to compute a single average propagation velocity, more detailed information about spatial variations in propagation velocity requires higher density magnetometer arrays. Finally, the method is validated with simultaneous MGG and serosal electromyography measurements in a porcine subject.     

The ancient and modern history of EM ground-wave propagation

Radio-wave transmission over the surface of the Earth is a subject of enquiry going back to the beginning of the century. In this review, an attempt is made to describe the ground-wave mechanism that is omni-present. We first call attention to the early analytical contributions of Zenneck and Sommerfeld, based on a flat-Earth model. The subsequent controversies, particularly with regard to the role of the Zenneck surface wave, are outlined. Further developments by other pioneers, such as van der Pol, Fock, Bremmer, Norton, and Millington, are reviewed, and an attempt is made to put these in a modern context. We also show that the trapped surface wave can be a significant contribution to the total ground-wave field, when the Earth boundary is sufficiently inductive. Mixed-path theory and confirming model tests by Ray King are described briefly, along with calculated propagation curves for twoand three-section paths. The bibliography includes references to related topics, such as tropospheric refraction and topographic influences     

On excitation of the surface wave on the plane surface of an electrically conducting medium with high conductivity by a vertical aperture,the Zenneck wave

The efficiency of excitation of the surface wave, in particular, the Zenneck wave on the plane boundary of an electrically conducting medium with high conductivity by a vertical aperture is introduced and analyzed.     

A Surface Electromagnetic Wave on a Plane Ribbon with a Highly Conducting Surface

The properties of a surface wave directed by a plane ribbon made of a nonmagnetic material with a high surface conductivity are investigated. Using the model of an equivalent ribbon with an elliptical cross section, the complex slowing (corresponding to the real part) and attenuation (corresponding to the imaginary part) ratio is approximately calculated in the case when a wave propagates along the ribbon. Approximate estimation values for the phase, group, and energy velocities of the surface wave are also obtained.     

On the excitation of the Zenneck surface wave over the ground at 10 MHz

Using a planar earth model the infinite vertical aperture with a Zenneck wave variation is found to excite only the Zenneck wave with no radiation field. The finite vertical aperture excites a field which is similar to the Zenneck wave near the aperture but resembles the usual ground wave at large distances. Numerical results for various aperture heights are given for a frequency of 10 MHz for a homogeneous ground path.     

High-frequency scattering from the edges of impedance discontinuities on a flat plane

A high-frequency solution is presented for the scattering of a plane wave at the edges of surface impedance discontinuities on a fiat ground plane. Arbitrary uniform isotropic boundary conditions and a direction of incidence perpendicular to the edges of the discontinuities are considered for both the transverse electric (TE) and transverse magnetic (TM) cases. An asymptotic approximation of the exact solution given by Maliuzhinets and a spectral extension of the geometrical theory of diffraction (GTD) are used. Uniform expressions for the scattered field received at a point on the surface are given, including surface wave contributions. Numerical results are shown and in some examples they are compared with those obtained from a moment method (MM) solution.     

Diffraction by a line of curvature jump (a special case)

We consider the problem of diffraction of a short-wave field by a cylindrical body with the boundary that consists of a half plane and a convex-cylindrical surface jointed together along a straight line. The main feature of the problem under consideration is the jump of curvature of the boundary on the line. The problems with the Dirichlet, Neumann, and impedance boundary conditions are considered. The main terms of asymptotic expansion of wave fields for the problems are constructed     

Slow Surface Wave along a Compressible Plasma Slab

Slow surface wave phenomena are studied in a compressible plasma—dielectric interface, the structure being rectangular. Cases with plasma dielectric constant εp positive (i.e. plasma frequency is less than excitation frequency) and negative (i.e. plasma frequency is greater than excitation frequency) are both considered. The existence of tho ‘ forward ’ surface wave is observed in all cases. The Philbrick repetitive SK5-Analog Computer was used for computation. Limiting case of incompressible plasma slab is also discussed.     

Electromagnetic Surface Wave Propagation over a Bonded Wire Mesh

The electromagnetic surface wave that can propagate over a square mesh of intersecting parallel wires is considered. A combined analytical and numerical method developed earlier is employed to deal with the interacting wire currents. For small mesh spacings, the propagation constant is found to be almost independent of the azimuthal direction of propagation. This is in agreement with previous results obtained by Soviet investigators who utilize averaged boundary conditions for analyzing such bonded wire meshes. However, for larger wire spacings, greater than about one tenth of a wavelength, there is a significant dependence on the direction of propagation over the mesh. The validity of describing the wire mesh in terms of an effective transfer inductance and related questions are discussed briefly in the Appendix.     

The Surface Wave on the Boundary between a Hyperbolic Magnetooptical Single-Axis Metamaterial and an Isotropic Dielectric

Journal of Communications Technology and Electronics - The propagation of the surface wave along the boundary between a hyperbolic magnetooptical single-axis metamaterial and an isotropic...     

压电晶体切向对声表面波陀螺刻度因子的影响

刻度因子是陀螺的重要指标,而压电晶体切向对声表面波(SAW)陀螺刻度因子有重要影响。首先以铌酸锂作为分析声波波传特性的基板材料,建立不同的波传角度和不同的切面与各种模态SAW波速的物理数学模型,接着探讨旋转扰动时二次旋转欧拉角与X切、Y切及Z切等铌酸锂晶体中的陀螺效应,分析不同切向刻度因子的变化规律。根据计算结果,铌酸锂晶体中X切Y传(XY)、128°Y切X传(128°YX)、30°ZX、ZX和150°ZX对应的声表面波陀螺刻度因子最大,同时也得出了适合应用于声表面波陀螺的相对敏感切向为声表面波波速接近于慢横波时对应的切向。     

基于DPT-CZT处理的LFMCW雷达参数估计

提出了一种基于DPT-CZT处理的速度-加速度联合估计方法。根据差拍信号相位在快、慢时间轴上的二维联合特性,沿其慢时间维进行DPT处理,可以消除快、慢时间线性耦合项,同时实现了慢时间维相位的降阶处理,从而可以获得目标速度-加速度的联合估计。为确保速度估计的无模糊性,采用CZT变换对目标可能存在的频段进行密集采样以提高频率测量的精度。给出了速度-加速度联合估计的具体实现步骤以及CZT处理中参数的确定。基于速度、加速度估计值对差拍信号进行补偿,从而可以对速度估计进行进一步修正并获取目标距离的估计。仿真结果验证了方法的有效性。     

The Coupling Between Forward Propagating Wave and Backward Propagating Wave for P>hotorefractive Surface Waves

The coupling between forward propagating wave and backward propagating wave of photorefractive surface waves (PR SWs) along the surface of photorefractive crystals (PRC) with periodic corrugations is studied for the first time. The influences of depth and period number of periodical corrugation structures on the coupling between the forward propagating PR SW and backward propagating PR SW are discussed. Especially the influence of nonlinearity on the coupling is studied for the first time. The reflectivity and transmissivity of PR SWs are calculated numerically using coupled-mode theory. The results are significant for the design of integrated optical device utilizing photorefractive surface waves.     

Surface wave scattering from a notch in a dielectric-covered groundplane: TE-mode analysis

026The problem of TE mode surface wave scattering from a rectangular notch in a dielectric-covered ground plane is considered. A Fourier-transform technique is used to express the scattered field in the spectral domain in terms of parallel-plate waveguide modes. The boundary conditions are enforced on the ground plane and the notch aperture to obtain simultaneous equations for the transmitted field inside the notch. The simultaneous equations are solved to obtain a solution in a fast convergent series, thus facilitating the numerical computation. The transmission, reflection, and scattering coefficients are found to oscillate as the notch width increases especially when the notch depth is comparable to and larger than one wavelength. A limited number of computations show that the reflected power loss is less than 2% when the notch width is less than one wavelength     

Kerr型介质界面上弱非线性TM表面波的传播特性

本文研究Ｋｅｒｒ型介质界面上弱非线性ＴＭ表面波的性质。数值计算表明了沿线性与非线性介质界面传播的ＴＭ表面波的自散焦特性。