scholarly journals Time-Domain Electromagnetic Scattering by Buried Dielectric Objects with the Cylindrical-Wave Approach for GPR Modelling

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 421 ◽  
Author(s):  
Cristina Ponti ◽  
Massimo Santarsiero ◽  
Giuseppe Schettini
Keyword(s):  
Time Domain ◽  
Ground Penetrating Radar ◽  
Electromagnetic Scattering ◽  
Current Source ◽  
Circular Cross Section ◽  
Cylindrical Wave ◽  
Wave Approach ◽  
Scattered Fields ◽  
Transmitting Antenna ◽  
Ground Penetrating

Electromagnetic modelling of ground penetrating radar applications to the survey of buried targets is a fundamental step in the interpretation of measured data from experimental campaigns. When pulsed source fields are employed, such a modelling is commonly performed through time-domain numerical techniques. The cylindrical wave approach is proposed here to solve the scattering of a pulsed field by circular cross-section cylinders buried in a semi-infinite medium. The field radiated field by a transmitting antenna is modelled using a line-current source. Theoretical solution is developed on a semi-analytical basis, through a spectral approach. Time and space spectra are employed to derive the scattered fields, and the final space–time dependence is found through an inverse Fourier Transform. The proposed approach allows an accurate modelling of a wide class of ground penetrating radar problems that are commonly simulated through two-dimensional layouts.

scholarly journals The Cylindrical Wave Approach for the Electromagnetic Scattering by Targets behind a Wall

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1262 ◽  
Author(s):  
Cristina Ponti ◽  
Giuseppe Schettini
Keyword(s):  
Electromagnetic Scattering ◽  
Circular Cross Section ◽  
Iterative Solution ◽  
Cylindrical Wave ◽  
Two Dimensional ◽  
Wave Excitation ◽  
Cylindrical Waves ◽  
Wave Approach ◽  
Scattered Fields ◽  
Final System

An overview of the cylindrical wave approach in the modeling of through-wall radar problems with targets hidden behind a dielectric wall is reported. The cylindrical wave approach is a technique for the solution of the two-dimensional scattering by buried circular cross-section cylinders in a semi-analytical way, through expansion of the scattered fields into cylindrical waves. In a through-wall radar application, the scattering environment is made by a dielectric layer between two semi-infinite half-spaces filled by air. For this layout, two possible implementations of the cylindrical wave approach have been developed in the case of plane-wave excitation. The first was an iterative scheme with multiple-reflection scattered fields, and the second was a fast and non-iterative solution, through suitable basis functions (i.e., reflected and transmitted cylindrical waves). Such waves take into account all the interactions of the source field with the interfaces bounding the dielectric layers and the targets. The non-iterative approach was also extended for excitation from the radiated field by a line source. A final system was derived for the computation of the scattered field by PEC or dielectric targets. Numerical results show the potentialities of the cylindrical wave approach in the modeling of through-wall radar, in particular in the evaluation of the scattered fields by human targets in a building’s interior, modeled with a two-dimensional approach.

Electromagnetic Scattering by a Metallic Cylinder Buried in a Lossy Medium With the Cylindrical-Wave Approach

2013 ◽  
Vol 10 (1) ◽  
pp. 179-183 ◽  
Author(s):  
Fabrizio Frezza ◽  
Lara Pajewski ◽  
Cristina Ponti ◽  
Giuseppe Schettini ◽  
Nicola Tedeschi
Keyword(s):  
Electromagnetic Scattering ◽  
Cylindrical Wave ◽  
Wave Approach ◽  
Lossy Medium ◽  
Metallic Cylinder

scholarly journals Study Effect of Objects Orientation in the Mediums On GPR Signal Reflections Using FDTD Simulation

2018 ◽  
Vol 3 (11) ◽  
pp. 73-77
Author(s):  
Aye Mint Mohamed Mostapha ◽  
Gamil Alsharahi ◽  
Abdellah Driouach
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Ground Penetrating Radar ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Ground Surface ◽  
Propagation Path ◽  
Fdtd Simulation ◽  
Ground Penetrating ◽  
Dielectric Objects

Ground penetrating radar (GPR) is a very effective tool for detecting and identifying objects below the ground surface.  based on  the propagation and reflection of high-frequency electromagnetic waves. The GPR reflection can be affected by many things like the type of objects orientation, their shapes ..ect. The purpose of this paper is to  study by simulation the effect of objects orientation in two different mediums (dry and wet sand) on the GPR signal reflection using Reflexw software which is based on a numerical method known as finite difference in time domain (FDTD).  The simulations that have been realized included a conductor  and dielectric objects. The results obtained have led us to find that the propagation path, the reflection strength and the signal form change with the change of object orientation and nature. To confirm the validity of the results, we compared them with experimental results previously published by researchers under the same conditions.

Analysis for Scattering of Non-homogeneous Medium by Time Domain Volume Shooting and Bouncing Rays

2021 ◽  
Vol 36 (3) ◽  
pp. 245-251
Author(s):  
Jun Li ◽  
Huaguang Bao ◽  
Dazhi Ding
Keyword(s):  
Time Domain ◽  
Electromagnetic Scattering ◽  
Electromagnetic Waves ◽  
High Efficiency ◽  
Homogeneous Medium ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Transient Electromagnetic ◽  
Frequency Domain Methods ◽  
Scattered Fields

In order to evaluate scattering from hypersonic vehicles covered with the plasma efficiently, time domain volume shooting and bouncing rays (TDVSBR) is first introduced in this paper. The new method is applied to solve the transient electromagnetic scattering from complex targets, which combines with non-homogeneous dielectric and perfect electric conducting (PEC) bodies. To simplify the problem, objects are discretized into tetrahedrons with different electromagnetic parameters. Then the reflection and transmission coefficients can be obtained by using theory of electromagnetic waves propagation in lossy medium. After that, we simulate the reflection and transmission of rays in different media. At last, the scattered fields or radiation are solved by the last exiting ray from the target. Compared with frequency-domain methods, time-domain methods can obtain the wideband RCS efficiently. Several numerical results are given to demonstrate the high efficiency and accuracy of this proposed scheme.

Cylindrical-Wave Approach for electromagnetic scattering by subsurface metallic targets in a lossy medium

2013 ◽  
Vol 97 ◽  
pp. 55-59 ◽  
Author(s):  
F. Frezza ◽  
L. Pajewski ◽  
C. Ponti ◽  
G. Schettini ◽  
N. Tedeschi
Keyword(s):  
Electromagnetic Scattering ◽  
Cylindrical Wave ◽  
Wave Approach ◽  
Lossy Medium

Modeling near‐field GPR in three dimensions using the FDTD method

Geophysics ◽  
1997 ◽  
Vol 62 (4) ◽  
pp. 1114-1126 ◽  
Author(s):  
Roger L. Roberts ◽  
Jeffrey J. Daniels
Keyword(s):  
Electrical Properties ◽  
Finite Difference ◽  
Time Domain ◽  
Near Field ◽  
Characteristic Impedance ◽  
Fdtd Method ◽  
Three Dimensions ◽  
Field Pattern ◽  
Scattered Fields ◽  
Transmitting Antenna

Complexities associated with the theoretical solution of the near‐field interaction between the fields radiated from dipole antennas placed near a dielectric half‐space and electrical inhomogeneities within the dielectric can be overcome by using numerical techniques. The finite‐difference time‐domain (FDTD) technique implements finite‐difference approximations of Maxwell's equations in a discretized volume that permit accurate computation of the radiated field from a transmitting antenna, propagation through the air‐earth interface, scattering by subsurface targets and reception of the scattered fields by a receiving antenna. In this paper, we demonstrate the implementation of the FDTD technique for accurately modeling near‐field time‐domain ground‐penetrating radar (GPR). This is accomplished by incorporating many of the important GPR parameters directly into the FDTD model. These variables include: the shape of the GPR antenna, feed cables with a fixed characteristic impedance attached to the terminals of the antenna, the height of the antenna above the ground, the electrical properties of the ground, and the electrical properties and geometry of targets buried in the subsurface. FDTD data generated from a 3-D model are compared to experimental antenna impedance data, field pattern data, and measurements of scattering from buried pipes to verify the accuracy of the method.

GPR attenuation and its numerical simulation in 2.5 dimensions

Geophysics ◽  
1997 ◽  
Vol 62 (2) ◽  
pp. 403-414 ◽  
Author(s):  
Tong Xu ◽  
George A. McMechan
Keyword(s):  
Time Domain ◽  
Ground Penetrating Radar ◽  
Finite Difference Time Domain ◽  
Superposition Method ◽  
Frequency Data ◽  
Buried Pipe ◽  
Ground Penetrating ◽  
Cole Model ◽  
Difference Time

Modeling of ground‐penetrating radar (GPR) data in 2.5 dimensions is implemented by superposition of 2-D finite‐difference, time‐domain solutions of Maxwell's equations for different horizontal wavenumbers. Dielectric, magnetic, and conductive losses are included in a single formulation. Attenuations associated with dielectric and magnetic relaxations are introduced by superposition of Debye functions at a set of relaxation frequencies and using memory variables to replace convolutions between the field variables and the decay functions. Better fits to data may always be obtained using the superposition method than by the Cole‐Cole model. Good fits to both loss‐tangent versus frequency data from lab measurements, and to 500 and 900 MHz field GPR profiles of a buried pipe and the surrounding layers, demonstrate the flexibility and viability of the modeling algorithm. Discrepancies between lab and in‐situ measurements may be attributed to scale differences and local variations that make lab samples less representative of the site than the GPR profile.

Sign in / Sign up

Export Citation Format

Share Document