Reflector distortions diagnosis from far-field amplitude pattern

1995 ◽  
Vol 43 (11) ◽  
pp. 1217-1225 ◽  
Author(s):  
O.M. Bucci ◽  
G. D'Elia ◽  
G. Romito
Keyword(s):  
Field Amplitude ◽  
Far Field ◽  
Amplitude Pattern

Reflector Distortions Diagnosis from Far-Field Amplitude Pattern

1995 ◽  
Vol 43 (11) ◽  
pp. 1217
Author(s):  
O.M. Bucci ◽  
G. D'Elia ◽  
G. Romito
Keyword(s):  
Field Amplitude ◽  
Far Field ◽  
Amplitude Pattern

Average Q and yield estimates from the Pahute Mesa test site

1987 ◽  
Vol 77 (4) ◽  
pp. 1274-1294
Author(s):  
R. W. Burger ◽  
T. Lay ◽  
L. J. Burdick
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Energy Levels ◽  
Source Model ◽  
Spectral Shape ◽  
Field Amplitude ◽  
Far Field ◽  
Source Models ◽  
Attenuation Models ◽  
Shape Data

Abstract Attenuation models, with and without frequency dependence, have been developed through analysis of time-domain amplitude measurements and teleseismic spectral shape data from Pahute Mesa nuclear explosions. The time-domain analysis is based on a near-field to far-field amplitude comparison. The near-field amplitude information is incorporated in two parameterized explosion source models (Mueller-Murphy and Helmberger-Hadley) based on analyses of near-field data. The teleseismic amplitude observations are from a large data set of WWSSN short-period analog recordings. For the narrow-band time-domain data, the various source and attenuation models are indistinguishable. We utilize the spectral shape data in the 0.5- to 4-Hz band as a constraint on the source-attenuation models at higher frequencies, concluding that either source model, when convolved with the appropriate frequency-dependent Q model, can be consistent with both the near-field and far-field time-domain amplitudes and the spectral shape data. Given the trade-off between source and attenuation models and the similarity of the different source models in the 0.5- to 4-Hz band, it is difficult to prefer clearly one source model over the other. The Mueller-Murphy model is more consistent with surface wave amplitude measurements because of larger predicted long-period energy levels. Whether or not frequency dependence is included in the attenuation model, the value of t* near 1 Hz is about 1.0 sec (assuming the Mueller-Murphy source model) or 0.8 sec (assuming the Helmberger-Hadley source model). This 0.2 sec difference results from greater 1-Hz energy levels for the Mueller-Murphy source model. Adopting an average attenuation model, predicted amplitudes and yields are shown to be within the uncertainty of the data for all the events analyzed.

The low frequency scalar diffraction by an elliptic disc

1967 ◽  
Vol 63 (4) ◽  
pp. 1273-1280 ◽  
Author(s):  
B. D. Sleeman
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Scattered Field ◽  
Low Frequency ◽  
Field Amplitude ◽  
Wave Number ◽  
Series Expansions ◽  
Far Field ◽  
Scalar Diffraction ◽  
Scattering Cross

SummaryThe problem of scalar Dirichlet diffraction of a plane wave by an elliptic disc is discussed. A scheme is given whereby the low frequency expansion of the scattered field may be readily obtained. Series expansions are obtained for the far-field amplitude up to and including the second order in the wave number. The first two terms of the scattering cross-section are also derived.

Far-field pattern determination from the near-field amplitude on two surfaces

1990 ◽  
Vol 38 (11) ◽  
pp. 1772-1779 ◽  
Author(s):  
O.M. Bucci ◽  
G. D'Elia ◽  
G. Leone ◽  
R. Pierri
Keyword(s):  
Near Field ◽  
Field Amplitude ◽  
Field Pattern ◽  
Far Field ◽  
Pattern Determination ◽  
Far Field Pattern

Acoustic Diffraction of a Plane Wave by Two Coplanar Parallel Perfectly Soft or Rigid Strips

1972 ◽  
Vol 50 (9) ◽  
pp. 928-939 ◽  
Author(s):  
D. L. Jain ◽  
R. P. Kanwal
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Normal Derivative ◽  
Field Amplitude ◽  
Far Field ◽  
Soft Or ◽  
Transmission Coefficients ◽  
Incident Plane ◽  
Acoustic Diffraction ◽  
Conducting Screen

The problem of diffraction of a normally incident plane acoustic wave by two parallel and coplanar infinite strips is considered. The assumed boundary conditions on the strips are the vanishing of either the total wave function or its normal derivative. Expressions are obtained for the first few terms of the series for the far-field amplitude and the scattering cross section when the wavelength is much larger than the distance between the outer edges of the strips. The corresponding results for two parallel and coplanar infinite slits in a soft or a rigid screen follow by applying Babinet's principle. This analysis also gives the transmission coefficients for the case of two infinite parallel slits in a thin conducting screen when the electric or magnetic field vectors of the incident plane monochromatic waves are polarized parallel to the edges of the slits.

FIELD OF A DIELECTRIC-LOADED, INFINITE CORNER REFLECTOR

1958 ◽  
Vol 36 (4) ◽  
pp. 438-445 ◽  
Author(s):  
A. W. Adey
Keyword(s):  
Radiation Resistance ◽  
Relative Permittivity ◽  
Field Amplitude ◽  
Far Field ◽  
Dielectric Cylinder ◽  
Corner Reflector

A study has been made of the effect on the radiating properties of an infinite corner reflector of loading its apex with a section of a dielectric cylinder of polystyrene and of a material with a relative permittivity of 4. Calculations of the radiation resistance and of the far-field amplitude have shown them to be sensitive to the presence of the loading, particularly for small spacings of the feeding element from the apex.

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