Applicability of the existing procedure for measuring the specular reflection coefficients of millimeter radio waves under strong refraction conditions

1984 ◽  
Vol 27 (10) ◽  
pp. 853-855
Author(s):  
L. M. Lobkova ◽  
N. I. Mishareva ◽  
V. V. Stel'makh ◽  
Yu. P. Mikhailyuk ◽  
A. I. Nadobenko ◽  
...  
Keyword(s):  
Specular Reflection ◽  
Reflection Coefficients ◽  
Radio Waves

Ionization profile of meteors from simultaneous video and radio forward scatter observations

2020 ◽  
Author(s):  
Hervé Lamy ◽  
Michel Anciaux ◽  
Sylvain Ranvier ◽  
Antoine Calegaro ◽  
Carl Johannink
Keyword(s):  
Peak Power ◽  
Specular Reflection ◽  
Radio Waves ◽  
Line Density ◽  
Science And Engineering ◽  
Forward Scatter ◽  
Electron Line ◽  
Power Profile ◽  
Video Observations ◽  
Polarization Factor

<p>In this study, optical video observations of meteors with the CAMS (Camera for All-sky Meteor Surveillance)-BeNeLux network and radio forward scatter observations with the BRAMS (Belgian RAdio Meteor Stations) network obtained on 4-5 October 2018  are combined in order to obtain an ionization profile along a meteor path.</p><p>The trajectory, initial speed and deceleration parameters of a given meteor are provided by the CAMS-BeNeLux data. For a given trajectory, the positions of the specular reflection points for radio waves are computed for each combination of a given BRAMS receiving station and the BRAMS transmitter. For each receiving station which recorded a meteor echo (depending on the geometry and the SNR ratio), the power profile is computed and the peak power values of the underdense meteor profiles are used to determine the ionization (electron line density) at the various specular reflection points along the meteor path. This is done using the McKinley (1961) formula which is strictly valid for underdense meteor echoes.  We discuss how we compute the gains of the antennas, the polarization factor, and how the peak power values are transformed from arbitrary units into watts using the signal recorded from a device called the BRAMS calibrator. We also discuss how to extend this study to overdense meteor echoes or those with intermediate electron line densities.</p><p>Finally, these results are combined with a simple ablation meteor model in order to obtain an estimate of the initial mass of the meteoroid.</p><p>Mc Kinley D.W.R., Meteor science and engineering, Mc Graw-Hill eds, 1961</p>

Multiple weights in diffraction stack migration

Geophysics ◽  
1993 ◽  
Vol 58 (12) ◽  
pp. 1820-1830 ◽  
Author(s):  
M. Tygel ◽  
J. Schleicher ◽  
P. Hubral ◽  
C. Hanitzsch
Keyword(s):  
Ray Tracing ◽  
Seismic Data ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Weight Vector ◽  
Reflection Coefficients ◽  
Dynamic Information ◽  
Data Set ◽  
Kirchhoff Migration ◽  
Multiple Weights

Three‐dimensional (3-D) prestack diffraction‐stack migration methods (often called Kirchhoff migration/inversion) play a fundamental role in seismic imaging. In addition to estimating the location of arbitrarily curved reflectors and the angle‐dependent reflection coefficients upon them, they can also be used to provide useful kinematic and dynamic information about the specular reflection ray that connects the source and receiver via the unknown reflecting interface. This is achieved by performing a diffraction stack more than once upon the same seismic data set using identical stacking surfaces but different weights. Some of these weights can be applied simultaneously, i.e., as a weight‐vector. The approach offers the possibility of determining various useful quantities that help to compute and interpret migrated reflections. The vector‐weighted diffraction stack is principally intended to economize the amplitude‐preserving migration that normally would require a large amount of dynamic ray tracing. A simple 2-D synthetic example shows how the method works in principle.

scholarly journals Wave structure at radar irradiation of homogeneous absorbing media

2021 ◽  
Vol 2140 (1) ◽  
pp. 012020
Author(s):  
V P Butukhanov ◽  
Ju L Lomukhin ◽  
E B Atutov
Keyword(s):  
Field Strength ◽  
Plane Wave ◽  
Electric Field ◽  
Specular Reflection ◽  
Wave Structure ◽  
The Other ◽  
Reflection Coefficients ◽  
Propagating Waves ◽  
The Media ◽  
Absorbing Media

Abstract The work is devoted to the study of the structure of waves excited in bordering media under radar irradiation of both smooth and rough interfaces. It is found that counter propagating waves are excited in bordering absorbing media, which determine backward reflection at the interface. On the other hand, the reflection of the counter propagating wave excites waves with a negative angle of refraction. It was found in this work that when the interface is irradiated with a plane wave during polarization, when the electric field strength vector lies in the plane of incidence, the backward reflection and the refracted wave are increases, and the specular reflection decreases. Electrodynamics models of the back reflection coefficients are developed for both the case of smooth and for the case of uneven interfaces between the media.

DIURNAL VARIATIONS IN THE NUMBER OF SHOWER METEORS DETECTED BY THE FORWARD-SCATTERING OF RADIO WAVES: PART II. EXPERIMENT

1955 ◽  
Vol 33 (10) ◽  
pp. 600-606 ◽  
Author(s):  
P. A. Forsyth ◽  
C. O. Hines ◽  
E. L. Vogan
Keyword(s):  
Specular Reflection ◽  
Forward Scattering ◽  
Diurnal Variations ◽  
Radio Waves ◽  
Forward Scatter ◽  
Transmission Path ◽  
Signal Rate ◽  
Cedar Rapids ◽  
Good Agreement

The theory developed in Part I is applied to derive the expected diurnal variations of the meteor signal rate for four showers as observed by means of a particular forward-scatter transmission path (Cedar Rapids – Ottawa). These results are then compared with the experimental signal rates. The good agreement obtained indicates that the approximations inherent in the theory are sufficiently accurate for practical purposes. The results also indicate that very few meteors, if any, are observed under conditions which do not satisfy the requirements for specular reflection.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

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