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A new expression of a Gaussian beam derived by using a spectral domain method is applied to the scattering problem from a hemispherical boss on a conducting plane. On the method of images, the original problem is reduced to that of the scattering of two Gaussian beams by a full sphere. The scattered fields are expressed in simple closed forms which are valid when the diameter of the boss is comparable to or less than the Gaussian beamwidth. The difference between the bistatic radar cross section of a Gaussian beam and that of a plane wave is discussed. Index Terms--Boss, Gaussian beam, radar cross section (RCS), scattering.

The near-field distribution in the case of the normal incidence to the Luneberg lens reflector is numerically obtained by using the modal expansion technique and point-matching method. As a model of the Luneberg lens, six different homogeneous media is used. A microwave experiment was also performed. Index Terms - Electromagnetic scattering, Luneberg lens reflector, microwave experiment, point-matching method.

Electromagnetic scattering of a Gaussian beam from a semicircular boss which protrudes above a conducting plane is investigated. The theoretical analysis for scattering is based on Kozaki's approximation, which makes it possible to express the Gaussian beam as a product of plane wave and weight function results. The scattered fields are expressed in simple closed forms which are valid when the diameter of the boss is comparable to or less than the Gaussian beamwidth. The numerical computations are performed to find that the angular bistatic RCS (radar cross section) of the Gaussian beam is much broader in scattering pattern than the plane wave case.

We performed analysis of a planar waveguide with arbitrary index variations. We obtained numerical results for the propagation coefficient by using first-order Langer and Liouville transformations. The accuracy of the numerical results is confirmed by a comparison with those obtained by other methods. [C] 2001 Optical Society of America OCIS codes: 230.0230, 230.7370, 230.7390, 260.2030.

For purpose of finding the dielectric constant, a new expression of the beam scattering is obtained by using the boundary element method (BEM) with extended boundary conditions. Comparision between with and without resonant condition was made for total scattered power. To find the accuracy, convergence property of the total scattered power versus divided number has been examined. To check the boundary conditions at the corner of the scatter, the electric field difference between inner and outer side has also been calculated and confirmed. Total electric field distributions in space are illustrated for the plane and beam wave. Microwave experimented was also performed. Index Terms--Boundary element method, dielectric rectangular cylinder, Gaussian beam.

Ionograms provide the main source of information about the electron densityprofile in the ionosphere. Some procedures have been presented for the calculation of real height profiles from ionograms. However, they usually have unacceptable errors within the valley layer of the electron density profile. In this paper, we derive a new estimating method which measures the electron density profile from propagation delay times. In order to verify the approach, the numerical experiments, which are carried out by taking the inverse fast Fourier transform of the reflection coefficient, are adopted. According to these results, it is possible to estimate the electron density profile in a one-peak profile within 1.5% errors, including the valley layer. The results show that our method gives a very accurate electron density profile. [ABSTRACT FROM AUTHOR]

This paper describes the numerical results and derivation of the partial reflected waves from a square-law medium in which a Gaussian beam is incident. First the WKB solution for the wave equation in the square-law medium is presented along with approximate solution for the first, second and third reflected waves can not be found by means of the WKB solution. An approximate expression for the partial reflected waves between two reflected beams is derived by Bremmer series. It is found that the partial reflected waves do not depend on the spot size of the beam and are basically proportional to the gradient of the permittivity. The theoretical results are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Analytical results by the integral equation method are described for the problem of electromagnetic scattering from perfectly conducting polygonal cylinders with TE and TM wave incidence. This approach is extended to the case of TE wave scattering by a set of perfectly conducting polygonal cylinders. In the presence of several conducting cylinders the mutually interacting surface current densities are used for deriving the integral equations. The latter are reduced to simultaneous equations by step function approximation of the current distributions. Numerical examples include the surface current distributions on a concave conducting cylinder and multiple rectangular cylinders and their scattering patterns as well as the near field distributions, which have not been evaluated extensively to date. It is found that a strong standing wave is caused in the electric field between the rectangular cylinders due to multiple scattering. To confirm validity of the theory, a model experiment is performed at microwave frequency. It is confirmed that the theoretical experimental results are in good agreement. The results of the present paper provide a calculation model for wave propagation in an urban community. They can be used as a basis of such propagation. [ABSTRACT FROM AUTHOR]