Maximum electromagnetic coupling to a nearby conducting strip through narrow and wide slits in a parallel-plate waveguide

The problems involved in electromagnetic coupling to a nearby conducting strip through narrow and wide slits in a parallel-plate waveguide (PPW) are discussed as simplified models of the two-dimensional (2-D) problems of aperture-coupled and proximity-coupled microstrip structures while focusing on radiative coupling mechanisms and perfect matching methods. These matching mechanisms exemplify general matching methods for use in small flush antenna structures. Finally, the similarity between the role of the nearby strip and the phasing unit of the recently reported crossed-field antenna structure is also discussed.     

Electromagnetic coupling through small apertures in a conducting screen

The electromagnetic field coupling through small apertures illuminated by an arbitrary incident plane wave is discussed for general aperture shapes. A set of new integral equations in a form highly amenable to numerical solution techniques is derived. Based on the application of the Rayleigh series method, an analytical solution is obtained for the first few terms of the expansion of the apertureE- field of a circular aperture. Numerical results are also constructed for the aperture field and the diffracted field of small rectangular apertures and compared with those of the circular apertures.     

Reflection coefficient of a parallel-plate waveguide illuminating a conducting sheet

The TEM mode reflection coefficient is analyzed for a symmetric parallel-plate waveguide composed of adjacent conducting wedges and radiating into a perfectly reflecting sheet oriented normal to the guide axis. Using the wedge diffraction method, the reflection from the conducting sheet is treated in terms of successive contributions or bounces that describe the interacting waves between the waveguide wedges and the reflecting sheet. For guides with small wedge angles (less than 75 degrees), the interacting waves can be treated as plane waves, and thus the reflection coefficient can be obtained through what is referred to as the self-consistent procedure. For guides with large wedge angles each of the interacting bounce waves can be resolved into component cylindrical waves. The total reflection from the sheet is then obtained by summing these iterative contributions. Calculated results from this analysis are in good agreement with measurements.     

Electromagnetic coupling to an infinite wire through a slot in a conducting plane

The problem of electromagnetic coupling to a long wire behind a slot-perforated conducting plane is considered by the method of moments. An equivalent circuit is obtained for the transmission line mode of the wire-slot system. An interesting result of the analysis is that, when the wire is terminated in loads for maximum power transfer, orders of magnitude more power may be transferred through the slot when the wire is present than when the wire is absent.     

Characteristics of a parallel-plate waveguide with a narrow slit in its upper plate

A parallel-plate waveguide with a narrow slit in its upper plate is investigated. The magnetic current induced in the slit is obtained from an integral equation whose kernel is approximated to a logarithmic function. From knowledge of the magnetic current, the normalised conductance and susceptance of the slit are computed.     

Electromagnetic coupling to a cable through apertures

Electromagnetic field penetration through apertures is investigated numerically and experimentally. The coupling to a cable located behind an aperture is determined in terms of the open circuit voltage of the cable. A square and a circular aperture are taken as examples, and the open circuit voltage is calculated and verified by an experiment. The apertures are modeled by employing Babinet's principle and solving the complementary flat plate problem using wire-grid modeling. Comparisons with radar cross section measurements were also made to verify the wire-grid modeling.     

Electromagnetic scattering by a conducting strip with a multilayerelliptic dielectric coating

The scattering of an electromagnetic plane wave by a conducting strip coated with a multilayer elliptic dielectric is considered. The solution of this problem is carried out by using an expansion of the electromagnetic field in terms of Mathieus functions and by implementing an efficient procedure for the “treatment” of the boundary conditions. This procedure could be a useful tool for checking the accuracy of numerical techniques widely used in electromagnetic compatibility, as it allows the solution of one of the few canonically solvable scattering problems involving perfectly conducting objects with sharp edges and inhomogeneous dielectrics. Many numerical results concerning the scattering cross section per unit length are provided and, where possible, they are compared with already available results. We consider only perpendicular incidence, although oblique generalization is conceptually easy     

Plane wave diffraction by a slit in a perfectly conducting plane and a parallel complementary strip

The diffraction of plane electromagnetic waves by the configuration formed by a slit in a perfectly conducting plane and a parallel complementary strip is investigated. The related boundary-value problem is formulated into a modified matrix Wiener-Hopf equation. The factorization of the kernel matrix is accomplished through Abrahams’ method and the modified matrix Wiener-Hopf equation is first reduced to a pair of coupled Fredholm integral equations of the second kind and then solved by iterations. Several numerical results illustrating the effects of various parameters such as the spacing between the slit and the strip and their width on the diffraction phenomena are presented.     

有限厚导电平板上任意缝隙的耦合特性分析

利用边界积分方程法结合广义网络原理和连接算法分析了有限厚导电平板上任意二维缝隙的散射及传输特性,并以ＴＥ波为例给出了具体的分析方法和结果。该方法不仅可用于任意形状和复杂介质填充缝隙的分析,还可考虑缝所在导体板的厚度。边界积分方程和连接算法的采用,使得分析该问题所需的计算机容量大大降低,计算效率大大提高。     

Field distribution in a flanged parallel-plate waveguide

Field distributions in a flanged parallel-plate waveguide have been computed using the Weber-Schafheitlin integral technique. Equiamplitude and equiphase contours are presented in graphical forms for a specific choice of parameters.     

Mode coupling through wall losses in a waveguide

The differential equations for the waveguide modes are utilised to investigate the coupling effects of a low wall impedance Zs, on the modes. Particular attention is given to the case of two degenerate modes.     

An approximate solution for coupling to a coaxial waveguide whichterminates at a conducting wedge

An integral equation is derived to approximate the aperture electric field for a coaxial waveguide that terminates at a conducting wedge. The integral equation is derived by retaining the standard kernel for the infinite-flange case and adapting the solution for the two-dimensional conducting wedge for use as the excitation term. The solution of this equation gives rise to an approximation to the TEM open-circuit voltage. Because only the excitation term is modified, the equation is useful for connectors that are greater than about one wavelength away from the corner. Theoretical and experimental results for the power transmitted down the coax are presented     

Wave propagation inside a two-dimensional perfectly conducting parallel-plate waveguide: hybrid ray-mode techniques and their visualizations

This work is intended as an educational aid, dealing with high-frequency (HF) electromagnetic wave propagation in guiding environments. It is aimed at advanced senior and first-year graduate students who are familiar with the usual engineering mathematics for wave equations, especially analytic functions, contour integrations in the complex plane, etc., and also with rudimentary saddle-point (HF) asymptotics. After an introductory overview of issues and physical interpretations pertaining to this broad subject area, detailed attention is given to the simplest canonical, thoroughly familiar, test environment: a (time harmonic) line-source-excited two-dimensional infinite waveguide with perfectly conducting (PEC) plane-parallel boundaries. After formulating the Green's function problem within the framework of Maxwell's equations, alternative field representations are presented and interpreted in physical terms, highlighting two complementary phenomenologies: progressing (ray-type) and oscillatory (mode-type) phenomena, culminating in the self-consistent hybrid ray-mode scheme, which usually is not included in conventional treatments at this level. This provides the analytical background for two educational MATLAB packages, which explore the dynamics of ray fields, mode fields, and the ray-mode interplay. The first package, RAY-GUI, serves as a tool to compute and display eigenray trajectories between specified source/observer locations, and to analyze their individual contributions to wave fields. The second package, HYBRID-GUI, may be used to comparatively display range and/or height variations of the wave fields, calculated via ray summation, mode-field summation, and hybrid ray-mode synthesis.     

Monopole antenna radiation into a parallel-plate waveguide

A rigorous solution of coaxially fed monopole antenna radiation into a parallel-plate waveguide is obtained. The Fourier transform/series representations are used to represent scattered fields and the boundary conditions are enforced to obtain the simultaneous equations for discrete modal coefficients. Fast convergent series of the reflection coefficient is obtained and compared with other existing results     

电磁波对不规则地面上架空线的影响

对不规则金属地表面上有限长架空线受平面电磁波影响的问题提出了一个有效的解决方案 :采用复合矩量法求解不规则地表面对平面电磁波的散射 ,再针对具有分布源的架空通信传输线 ,采用解析与数值相结合的方法求解。详细地介绍了求解平面电磁波对不规则地面上架空线影响的理论分析和计算过程 ,并且针对实际工程应用的典型参数给出了计算实例并讨论了计算结果。该方案也适用于航行轮船及待发射飞行器表面上通信电缆的电磁干扰问题     

Electromagnetic penetration through apertures in conducting surfaces

In designing hardened systems, one must be able to characterize as well as quantitatively determine the penetration of EMP signals through apertures of general shapes in structures of varying configurations. In this paper a tutorial review of a number of methods for analyzing such aperture problems is presented with an emphasis on techniques. The discussion presented herein is reasonably self-contained and is supplemented by references to classical as well as current approaches to the aperture problem. An extensive set of representative numerical results is included.     

Mutual coupling between two waveguide radiators on a conducting concave sectoral surface

An approximate theoretical expression for the mutual coupling between two waveguide radiators directed radially inward and located on a perfectly conducting concave sectoral surface has been developed using reaction concept. The radius of curvature of the surface is assumed to be large so that the apertures can be considered on locally plane surface. The theoretical and experimental results show close agreement.     

Electromagnetic coupling to a conducting wire behind an aperture of arbitrary size and shape

The electromagnetic coupling to a conducting wire behind an aperture in a plane conducting screen is analyzed. The aperture can be of arbitrary size and shape. The wire can be of finite length, with or without terminating loads, or of infinite length. The electric current on the wire and the equivalent magnetic current over the aperture region are calculated by the method of moments. An equivalent circuit for the effect of the aperture on the transmission line mode of the wire is derived.     

TE-scattering and reception by a parallel-plate waveguide array

TE-wave scattering and reception by a parallel plate waveguide array is Investigated. A Fourier-transform technique is used to express the scattered field in the spectral domain. The boundary conditions are enforced on the conducting surface and the array apertures to obtain simultaneous equations for the transmitted field inside the waveguide. The simultaneous equations are solved to obtain the transmitted field in a series representation whose first term is the Kirchoff solution. The behavior of the far-zone scattered field and the transmission coefficient are studied in terms of the scattering angle, array size, and frequency