J. Van Bladel

Some remarks on green's dyadic for infinite space

The validity of the often used dyadic -(\jmath + \frac{1}{k^{2}}\nabla \nabla )\frac{e^{-jkR}{4\piR} to compute the electric field inside a current-carrying region is investigated. It is found that care must be exercised in the definition of the integrals, which should be taken as principal values around the field point.

Scattering by perfectly-conducting rectangular cylinders

The problem of determining the fields scattered by a perfectly-conducting rectangular cylinder is reduced to the solution of an integral equation. This equation is then solved by digital computer methods. Data are given for surface currents, radiation patterns and scattering cross sections for both E - and H -incident waves.

Polarizability of some small apertures

The basic integral equations for the electrostatic and magnestostatic problems are reviewed. These equations are solved with a digital computer for four typical aperture shapes. The results of the calculations are compared with Cohns experimental values. Some data are given concerning the corresponding acoustic problems.

Low-frequency scattering by rectangular cylinders

An integral equation formulation is used to investigate potential problems associated with low-frequency scattering by both dielectric and perfectly conducting cylinders of rectangular cross section. Induced dipoles and scattering cross sections are obtained for 1) waves with \bar{E} or \bar{H} parallel to the axis, and 2) directions of propagation perpendicular and parallel to the broad side of the rectangle.

Electrostatic dipole moment of a dielectric cube

SummaryThe electrostatic dipole moment of a dielectric cube introduced into a uniform electrostatic field can be determined by solving an appropriate surface integral equation. High-speed digital computers have been employed to solve the matrix approximation to this equation.

FIELDS IN CAVITY-EXCITED ACCELERATORS

Field configuration and resonant frequency are determined for the lowest azimuthally‐independent mode of a coaxial cavity surrounding a circular tube, Several values of the width of the coupling gap are considered, and the central problem consists in determining the tangential electric field Et in that gap. It was found that the fields near the axis of the accelerator are quite insensitive to the actual profile of Et, and that satisfactory results are obtained by assuming Et to be constant. The problem is repeated for a parallel plane configuration, with the purpose of investigating the influence of the flattening of the cavity. Computations show that the two configurations yield fairly similar results.

Magnetic polarizability of some small apertures

Curves are given for the dimensionless magnetic polarizabilities \nu_{mx} and \nu_{my} of a few characteristic apertures. The relevant integral equations are solved by the moment method. The subareas are triangular, and the basis functions for the triangles touching an edge take the edge singularity into account. Some data are included for a few typical ring-shaped apertures.

Cut‐Off Frequency in Two‐Dielectric Layered Rectangular Wave Guides

Equations for the modes and eigenvalues of two‐dielectric layered rectangular wave guides with cross sections as in Fig. 1(a), (b), and (c) are derived. From these equations are plotted graphs of cut‐off frequency over a range of geometric and dielectric parameters sufficiently wide to cover most requirements of design.

Low-frequency scattering by cylindrical bodies

SummaryGeneral formulas are derived for the scattered amplitude and scattering cross-section of metallic and dielectric cylinders immersed in a low-frequency field. The shape of the cylinders is left unspecified. The two fundamental polarizations (i.e. eitherE orH parallel to the axis) are considered.

Scattering of low-frequency E-waves by dielectric cylinders

The dominant term in the scattering pattern of an E -wave by a dielectric cylinder is known to be omnidirectional. In the present communication we investigate the next-order term in k , the wave number.