摘要:

An exact formulation for scattering from a junction between a coaxial and a radial waveguide is given in terms of an integral equation at the junction. An approximate solution to the integral equation, derived by the method of moments with attention to asymptotics, yields resultsforjunction sizes up toa fewwavelengths. Another approximation gives a simple algebraic result in the low frequency limit. Comparisons are made between thetwo approximations forrepresentativeparameters.The transient response is derived using numerical inverse transform techniques. Geometric features suitable for parametric inverse studies are discussed in both the time and frequency domains.

ISSN:0920-5071    

DOI:10.1163/156939387X00162

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A radiance value of a target pixel recorded by a remote sensor can be decomposed into three components: (1) attenuated target signature, (2) pure atmospheric radiation, and (3) the contribution made by the ground through the atmospheric scattering process. Given the meteorological and optical parameters of a layer-structured atmosphere, its transmittance and radiance distribution can be accurately calculated with a plane-parallel radiative transfer model. For a uniform surface, the ground contribution can be obtained by comparing radiances for an atmosphere over a black but non-emitting surface and the same atmosphere with an underlying ground of given albedo or temperature. For an inhomogeneous surface, the first two components remain the same as long as the surface is a plane. The third may be estimated using the locally averaged top-of-atmosphere radiance. An atmospheric point spread function is calculated by a Monte Carlo approach and is used for retrieving the ground signature through a deconvolution procedure.

ISSN:0920-5071    

DOI:10.1163/156939387X00171

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A general geometrical optics formulation is derived for refraction at a planar interface between arbitrarily lossy media. Using a Fourier transform technique, we determine the exact field in one medium due to a point source in another. A high-frequency asymptotic solution is found involving complex ray angles and a complex refraction point on the interface. This solution and two other ray formations used by other researchers for the same problem are compared against a numerical evaluation of the exact field expression. The solution with the complex refraction point gives the most generally useful results.

ISSN:0920-5071    

DOI:10.1163/156939387X00180

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The exact solution of the two-dimensional Sommerfeld half-plane problem is obtained with a path integral approach. The approach relies on the Riemann space associated with this problem but does not require discretization nor a transformation to the corresponding heat conduction problem. A new intrinsic symmetry property of the half-plane problem solutions is revealed and is connected to the characteristics of the underlying Riemann space. An endpoint rather than a stationary point argument reproduces Keller's GTD results from the path integral expression.

ISSN:0920-5071    

DOI:10.1163/156939387X00199

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939387X00207

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939387X00216

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor