Scattering of radio waves by a two-layer medium with a weakly reflecting rough boundary

1998 ◽  
Vol 41 (7) ◽  
pp. 600-609
Author(s):  
M. V. Kachan ◽  
S. F. Pimenov ◽  
N. A. Stepanova
Keyword(s):  
Rough Boundary ◽  
Radio Waves ◽  
Layer Medium

scholarly journals Evaluation of Electrophysical Properties of Soils in the Slope Zones of the Foundation During GPR Survey

2021 ◽  
Vol 18 (6) ◽  
pp. 88-107
Author(s):  
V. V. Pupatenko ◽  
Yu. A. Sukhobok ◽  
G. M. Stoyanovich
Keyword(s):  
Survey Methods ◽  
Geophysical Methods ◽  
Propagation Speed ◽  
Transport Infrastructure ◽  
New Method ◽  
Radio Waves ◽  
Cross Sectional ◽  
Initial Information ◽  
Inclined Surfaces ◽  
Layer Medium

The article describes a new method for conducting a ground penetrating radar survey of slope zones of soil objects of transport infrastructure. In the lithological section of these objects, there are sub-horizontal and inclined soil boundaries, as well as slope zones. Traditional survey methods (drilling, pitting), as well as the standard GPR method, make it possible to reliably survey at these objects, as a rule, only the zones under the horizontal main ground of the subgrade and sub-horizontal sections of the ground outside its boundaries. Survey under inclined surfaces is often difficult or technically impossible; geophysical methods, just like traditional ones, provide initial information that is exceedingly difficult for further decoding. The sections are filled with re-reflections and noises, and the process of decoding them is associated with great methodological problems.This paper presents a new method for determining speed of propagation of radio waves in the slope zones of the foundation. The initial information is the data obtained during the survey using the common depth point (CDP) method, using a well-known survey technique and a standard set of hardware. The novelty of the article results is determined by the algorithm for processing the measurement results developed by the authors. The software implementation made on its basis makes it possible to obtain the hodograph equation considering the slope of the layers. Defining geometric characteristics of embankments associated with the presence of slopes of variable steepness have been considered. A technique for calculating propagation speed of radio waves for a two-layer medium with a boundary inclined to the scanning surface has been proposed. The validity of the developed method was verified using finite-difference time-domain modelling.The article provides examples of practical application of the developed method in the GPR survey of real track foundation objects (transport infrastructure objects). The method proposed in the article makes it possible to increase the informative area of the surveyed diameters. At the same time, the accuracy of the GPR method is preserved, the area of its application for obtaining reliable information is increased to 60 % of the cross-sectional area of the foundation.

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.

Radio Waves Kill Insect Pests

1933 ◽  
Vol 148 (5) ◽  
pp. 272-273 ◽  
Author(s):  
J. H. Davis
Keyword(s):  
Insect Pests ◽  
Radio Waves

Ultra Short Baseline (USBL) Calibration for Positioning of Underwater Objects

2019 ◽  
Vol 2 (2) ◽  
pp. 73-85
Author(s):  
Bagus Septyanto ◽  
Dian Nurdiana ◽  
Sitti Ahmiatri Saptari
Keyword(s):  
Acoustic Wave ◽  
Scale Factor ◽  
Positioning System ◽  
Radio Waves ◽  
Short Baseline ◽  
Error Angle ◽  
Satellite Navigation System ◽  
The Earth ◽  
Underwater Positioning ◽  
Radio Signals

In general, surface positioning using a global satellite navigation system (GNSS). Many satellites transmit radio signals to the surface of the earth and it was detected by receiver sensors into a function of position and time. Radio waves really bad when spreading in water. So, the underwater positioning uses acoustic wave. One type of underwater positioning is USBL. USBL is a positioning system based on measuring the distance and angle. Based on distance and angle, the position of the target in cartesian coordinates can be calculated. In practice, the effect of ship movement is one of the factors that determine the accuracy of the USBL system. Ship movements like a pitch, roll, and orientation that are not defined by the receiver could changes the position of the target in X, Y and Z coordinates. USBL calibration is performed to detect an error angle. USBL calibration is done by two methods. In USBL calibration Single Position obtained orientation correction value is 1.13 ̊ and a scale factor is 0.99025. For USBL Quadrant calibration, pitch correction values is -1.05, Roll -0.02 ̊, Orientation 6.82 ̊ and scale factor 0.9934 are obtained. The quadrant calibration results deccrease the level of error position to 0.276 - 0.289m at a depth of 89m and 0.432m - 0.644m at a depth of 76m

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