Electric polarizability for a thick eccentric annular aperture with a floating inner conductor

An electrostatic potential penetration into an eccentric annular aperture in a thick conducting plane is investigated when an inner conductor is electrically floating. Conformal mapping is used to transform an eccentric annular aperture into a concentric aperture. The Hankel-transform and eigenfunction expansion is utilized to solve the boundary-value problem for a concentric annular aperture. Computation is performed to illustrate the electric polarizability, capacitance, and potential distribution for various aperture geometries.     

Solution of the nonlinear eigenvalue boundary-value problem for tm electromagnetic waves propagating in a Kerr-nonlinear layer by means of the cauchy problem method

The problem of propagation of TM electromagnetic waves in Kerr-nonlinear layer is considered. The problem is reduced to the solution of a nonlinear eigenvalue boundary-value problem for a system of two ordinary differential equations. A numerical method is proposed for solving the considered eigenvalue boundary-value problem. It is shown that the proposed method makes it possible to investigate more complicated types of nonlinearity. Numerical results are reported. The method is compared to another known technique and to the linear case.     

Hologram coherence effects

Holograms formed from opaque particles in a clear aperture illuminated with quasi-monochromatic, partially coherent light are considered. The method used to formulate the general boundary-value problem for the pair of wave equations propagating the mutual-coherence function is described. The effect of a reduction in spatial coherence on the resolution limit of a Fraunhofer (far-field) hologram is discussed. Bandwidth considerations of the same hologram define a usable far-field region from which resolvable reconstructions can be expected. The effects of spatial coherence upon Fresnel (near-field) holograms are shown, and experimental results that confirm these calculations are presented.     

Electromagnetic transmission through multiple circular apertures in a thick conducting plane

The boundary-value problem of electromagnetic wave scattering from multiple circular apertures in a thick conducting plane is rigorously solved. The eigenfunction expansion, integral transform, and superposition principle are utilized to represent the scattered field in the discrete and continuous modes. The boundary conditions are enforced to obtain a set of simultaneous equations for the discrete modal coefficients. The transmission coefficient is represented in a fast convergent series. Computation is performed to illustrate the behavior of transmission and coupling through multiple circular apertures in terms of the aperture geometry.     

Capacitance of Multiple Annular Apertures With Floating Inner Conductors

Capacitance of multiple annular apertures with floating inner conductors is investigated. A boundary-value problem associated with the capacitance of thick multiple annular apertures is solved rigorously based on the Hankel transform, eigenfunction expansion, and superposition. The formulation for calculating the capacitance of each annular aperture is obtained in a fast convergent series form. Computation is performed to show the behavior of the capacitance in terms of the geometry of multiple annular apertures.     

Radiation properties of a flanged parallel-plate waveguide loadedwith an ε-μ general anisotropic slab

In this analysis, the excitation is taken to be either (1) the lowest-order transverse electric (TE) or the lowest-order transverse magnetic (TM) (i.e. transverse electromagnetic) waves, or (2) a uniform, E- or H-polarized, incident plane wave. As a result of the anisotropy, cross-polarization effects are observed. The formulation of the boundary-value problem is carried out in the Fourier transform domain. Considerable contraction results by using previously developed matrix analysis techniques. In this way, a fruitful integral representation of the tangential components of the magnetic field is first derived in terms of the tangential components of the electric field at the excitation aperture. Next, and after imposing the boundary conditions at the aperture boundary surface, this representation is used as the starting point for a solution on the basis of a moment method (MM) approach using the eigenmodes as basis and weighting functions. Numerical results related to the reflection and coupling coefficients as well as the directive diagrams of the structure are presented in graphical form for various cases     

Numerical Solution of the Thomas–Fermi Equation for the Centrally Symmetric Atom

The computational aspects are analyzed of the Thomas–Fermi equation for a spherically symmetric and electrically neutral atom of finite size that is part of a solid. The limits are identified of the shooting method as a tool for solving a boundary-value problem for the equation. With an iterative method and the sweep method used in combination, a narrow parameter range is found in which the iterative process exhibits deterministic chaos.     

Input admittance and aperture field of flanged coaxial line radiating into layered half-space

The problem of a semi-infinite coaxial line opening into a layered half-space with arbitrary number of layers is investigated. An integral equation for the radial component of the aperture electric field is formulated and solved numerically using the Galerkin method. Numerical computations were performed for two layer half-space in a numerical example taken from a biomedical engineering application in the irradiation of composite biological tissues with a radio frequency wave. Results for the input admittance as well as the aperture field distribution are presented and comparison with existing literature is made.     

Least square collocation as applied to the analysis of strip transmission lines

The crude method of collocation applied for the solution of the boundary-value problems has been improved upon in a least square sense for solving complex problems in applied mechanics. In this letter, the least square collocation method is applied for the solution of the electrostatic field problem of the strip transmission line enclosed in a shielded box, which is a case of mixed boundary-value problem. Compared to the other previous numerical methods, this method is much less laborious, simpler, and faster, and the results agree well with those available in the literature.     

Theory of Periodic Dielect Waveguides

The propagation of electromagnetic waves along open periodic, dielectric waveguides is formulated here as a rigorous and exact boundary-value problem. The characteristic field solutions are shown to be of the surface-wave or leaky-wave type, depending on the ratio of periodicity to wavelength (d/lambda). The dispersion curves and the space-harmonic amplitudes of these fields are examined for both TE and TM modes. Specific numerical examples are given for the cases of holographic layers and for rectangularly corrugated gratings; these show the detailed behavior of the principal field components and the dependence of waveguiding and leakage characteristics on the physical parameters of the periodic configuration.     

A combined-source solution for radiation and scattering from a perfectly conducting body

A combined-source solution is developed for electromagnetic radiation and scattering from a perfectly conducting body. In this solution a combination of electric and magnetic currents, called the combined source, is placed on the surfaceSof the conducting body. The combined-source operator equation is obtained from theE-field boundary-value equation. It is shown that the solution to this operator equation is unique at all frequencies. The combined-field operator equation also has a unique solution, but it is not directly applicable to the aperture radiation problem. TheH-field andE-field operator equations fail to give unique solutions at frequencies corresponding to the resonant frequencies of a cavity formed by a hollow conductor of the same shape. The combined-source operator equation is solved by the method of moments. The solution, valid for a three-dimensional closed surfaceS, is then applied to a surface of revolution. Examples of numerical computations are given for a sphere, a cone-sphere, and a finite circular cylinder.     

Radiation from a spherical aperature antenna immersed in a compressible plasma

The exterior boundary-value problem for a sphere immersed in a compressible plasma medium is solved. The model is a perfectly conducting sphere excited by an aperture, in its surface, which has a specified distribution of the tangential electric field. The configuration is such that Maxwell's equations, when combined with the continuum theory of fluid dynamics, are separable. The sheath at the interface with the plasma is characterized by an absorptive boundary condition which assumes a linear relationship between the pressure and the mean velocity of the electrons. It is shown that the TM (transverse magnetic) waves are coupled with the electroacoustic waves, while the TE (transverse electric) waves are decoupled. Some numerical results are presented which show, in quantitative manner, the relative fraction of the total power which is radiated in the form of electroacoustic waves.     

Aperture Excitation of a Wire in a Rectangular Cavity

The problem of determining the currents excited on a wire enclosed within a rectangular cavity is considered. The wire and cavity interior are excited by electromagnetic sources exterior to the cavity which couple to the cavity interior through a small aperture in the cavity wall. It is assumed that the wire is thin, straight, and oriented perpendicular to one of the cavity walls. An integral equation is formulated for the problem in the frequency domain using equivalent dipole moments to approximate the effects of the aperture. This integral equation is then solved numerically by the method of moments. The dyadic Green's function for this problem are difficult to compute numerically; consequently, extensive numerical analysis is necessary to render the solution tractable. SampIe numerical results are presented for representative configurations of cavity, wire, and aperture.     

Hybrid method of state and parameter estimation for use in gradient techniques

The quasilinearisation method (or, equivalently, the parameter-influence-coefficient method) is currently preferred to the adjoint-variable method in solving the identification problem because it leads to a one-point boundary-value problem. It is shown that hybrid use of the two methods greatly reduces the number of first-order differential equations to be numerically integrated.     

Analysis of a coaxially fed monopole in a rectangular waveguide

The boundary-value problem of a coaxially fed monopole in a rectangular waveguide is solved. The technique of image method is applied to transform the original problem into an equivalent problem. A fast convergent series solution based on the Fourier transform and mode matching is presented. Our computation results compare favorably with other existing data.     

有机聚合物光波导延迟线研制的新进展

由于孔径效应和孔径渡越时间的限制,传统的相控阵雷达难以在大扫描角下实现大瞬时带宽,有机聚合物光波导延迟线可解决这一问题。先介绍了有机聚合物光波导延迟线的原理和优点,接着综述了三种延迟线：利用聚酰亚胺制成的4位有机聚合物光波导延迟线,多层结构的有机聚合物光波导延迟线,开关选择的超长有机聚合物光波导延迟线。     

Dual series solution to the scattering of plane waves from a binaryconducting grating

The problem of scattering of electromagnetic waves from a perfectly conducting grating with a periodic groove structure is considered. A system of dual series equations is derived by enforcing the electromagnetic boundary conditions; this leads to a boundary-value problem that is solved. The mathematics leading to the solution of the dual series system is derived from the equivalent Riemann-Hilbert problem in complex-variable theory and its solution. The solution converges absolutely and makes it possible to obtain analytical results, even where other numerical methods, such as the mode-matching method and spectral iteration methods, are numerically unstable. Consideration is also given to the relative phase values for the diffracted fields. The phase differences between the scattered fields resulting from two orthogonally polarized incident plane waves can be explicitly determined for any incidence angles and for any groove dimensions. Comparisons with results from the mode-matching method and the spectral-iteration method are also presented     

The variational method and the method of moments in the problem of plane wave scattering by a rectangular cavity in an impedance screen

The problem of electromagnetic plane wave diffraction by a rectangular cavity in an impedance screen is solved. The problem is reduced to solution of a Fredholm integral equation for the field function in the aperture. The equation has a symmetric kernel. Expressions for the angular distribution of the scattered far-field are obtained by the method of moments and the variational method. Numerical results are analyzed and compared.     

NEMP fields inside a metallic container with an aperture in onewall

The finite-difference time-domain (FDTD) method was used to study the nuclear electromagnetic pulse (NEMP) waves coupling into one metallic container through a small aperture in one face of the container. The incident electric fields of NEMP waves were expressed by double exponential forms with two different decay constants. The time-domain behavior of the electric field inside the metallic container excited by the waves was obtained by the FDTD method. The electric field distributions on various layers for the area of the aperture of 10×10 cm² were also calculated. It was found that the shielding effectiveness is greatly improved by a factor of 255 by reducing the area of the aperture from 10×10 to 1×1 cm² . The aperture filled with dielectric materials was also studied for shielding effectiveness. The coupled electric field inside the metallic container was round to be a nonlinear function of the relative dielectric constant of insulators filled in the aperture