scholarly journals A Novel Hybrid Algorithm for Transient Near-Field Scattering from Rough Surface in 2-D Case

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Wei Tian ◽  
Bing Wei ◽  
Qian Yang
Keyword(s):  
Rough Surface ◽  
Time Domain ◽  
Hybrid Algorithm ◽  
Near Field ◽  
Scattering Problem ◽  
Fdtd Method ◽  
Observation Point ◽  
Surface Integral ◽  
Field Radiation ◽  
Direct Numerical Integration

A novel hybrid algorithm is proposed to reduce the computation cost of the finite-difference time-domain (FDTD) method in calculating the transient near-field scattering from rough surface. The scattering problem is split into the FDTD calculation of equivalent sources on the contour enclosing rough surface and the calculation of the near-field radiation with the two-dimensional (2-D) time-domain Huygens’ principle. The radiation fields are found from a surface integral of the temporal convolution for which the direct numerical integration of the convolution is computationally expensive. In this paper, the 2-D time-domain Green’s function as the convolution kernel is approximated with a sum of exponential terms by using the Prony’s method. Then, the semianalytical recursive convolution (SARC) approach is applied to complete the update of the near-field radiation. Compared with the traditional FDTD, this hybrid algorithm can significantly reduce the memory usage and run time, especially for the large distance between the rough surface and observation point.

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.

Near-field scanning optical microscopy local luminescence studies of rhodamine dye

Open Physics ◽  
2010 ◽  
Vol 8 (3) ◽  
Author(s):  
Petr Klapetek ◽  
Juraj Bujdák ◽  
Jiří Buršík
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Optical Microscope ◽  
Far Field ◽  
Luminescence Signal ◽  
Local Topography ◽  
Field Radiation ◽  
Scanning Optical Microscopy ◽  
Rhodamine Dye ◽  
Near Field Scanning

AbstractThis article presents results of near-field scanning optical microscope measurement of local luminescence of rhodamine 3B intercalated in montmorillonite samples. We focus on how local topography affects both the excitation and luminescence signals and resulting optical artifacts. The Finite Difference in Time Domain method (FDTD) is used to model the electromagnetic field distribution of the full tip-sample geometry including far-field radiation. Even complex problems like localized luminescence can be simulated computationally using FDTD and these simulations can be used to separate the luminescence signal from topographic artifacts.

Near-field time-domain physical-optics and FDTD method for safety assessment near a base-station antenna

2003 ◽  
Vol 39 (5) ◽  
pp. 393-395 ◽  
Author(s):  
M. Martínez-Búrdalo ◽  
L. Nonídez ◽  
A. Martín ◽  
R. Villar
Keyword(s):  
Time Domain ◽  
Safety Assessment ◽  
Near Field ◽  
Fdtd Method ◽  
Base Station ◽  
Physical Optics

Modification to time domain near-field to far-field transformation for FDTD method

1997 ◽  
Vol 33 (25) ◽  
pp. 2132
Author(s):  
A. Giannopoulos ◽  
B.S. Randhawa ◽  
J.M. Tealby ◽  
A.C. Marvin
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Fdtd Method ◽  
Far Field ◽  
Field Transformation

Efficiency of Implicit Symplectic Finite-Difference Time-Domain Method for Near-Field Optics

2012 ◽  
Author(s):  
Ikuo Saitoh ◽  
Makoto Naruse
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Near Field ◽  
Fdtd Method ◽  
Conservation Of Energy ◽  
Near Field Optics ◽  
Polarization Control ◽  
Metal Nanostructure ◽  
Difference Time

We proposed a new method, implicit symplectic finite difference time domain (FDTD) method) which inherits the good properties from the conventional FDTD method, simplecticity and the conservation of energy. The proposed method is free from the Courant-Friedrics-Lewy condition at the same time. In this paper, we show our method is more efficient than the conventional FDTD method using a typical problem, a polarization control in optical near and far fields of the designing the shape of a metal nanostructure.

scholarly journals Modified Finite-Difference Time-Domain Method for Hertzian Dipole Source under Low-Frequency Band

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2733
Author(s):  
Minhyuk Kim ◽  
SangWook Park
Keyword(s):  
Finite Difference ◽  
Frequency Band ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Near Field ◽  
Fdtd Method ◽  
Low Frequency ◽  
Dipole Source ◽  
Static Approximation ◽  
Difference Time

In this paper, a modified finite-difference time-domain (FDTD) method is proposed for the rapid analysis of a Hertzian dipole source in the low-frequency band. The FDTD technique is one of the most widely used methods for interpreting high-resolution problems such as those associated with the human body. However, this method has been difficult to use in the low-frequency band as the required number of iterations has increased significantly in such cases. To avoid this problem, FDTD techniques using quasi-static assumptions in low-frequency bands were used. However, this method was applied only to plane wave excitation, making it difficult to apply to near-field problems. Therefore, a modified approach is proposed, involving the application of the FDTD technique with a quasi-static approximation to an electric and magnetic dipole problem. The results when using the proposed method are in good agreement with those from a theoretical solution. An example of comparison with the standard FDTD method is shown for illustrating the proposed method’s performance.

Sign in / Sign up

Export Citation Format

Share Document