The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A comparative study is carried out between two numerical simulation techniques—the surface integral equation (SIE) and the finite-difference time-domain (FDTD) methods—in order to characterize rough surface ground clutter relevant to forward-looking radar applications. Computational deficiencies in the SIE approach for analyzing scattering effects at grazing angles are outlined; motivations for the...
A novel technique to evaluate the Specific Absorption Rate (SAR) induced by a cellular phone using only a limited number of measurements on a surface for a curved phantom is proposed. A modal expansion of the Electric field induced in a head model by a cellular phone is used. This technique is first based on the use of equivalent currents on a closed surface according to Huygens principle. Then, using...
The finite-difference time-domain (FDTD) method is used to calculate the specific extinction cross-section (SECS) of the carbon-fiber powder at 35 GHz. The digitized models with a random process using the turning bands method are simulated for the carbon-fiber powder. The digitized models of the carbon-fiber power having 12500 to 5832000 cubical particles with sell sizes in the range of 7 to 100 µm...
The Finite-Difference Time-Domain (FDTD) method is used to simulate the electromagnetic problem of transmission through a metallic screen with slots of sizes and spacing that were chosen using the spatially shifted beam approach to achieve subwavelength focusing. The challenges related with the modeling of such sub-wavelength focusing meta-screens are demonstrated via the study of numerical convergence.
A novel image reconstruction algorithm for early breast cancer detection via ultra wideband microwave signals is proposed. In this algorithm, the backscattered electric and magnetic intensities are measured and combined in a novel way to detect cancerous growth. Specifically, a power calculation is performed wherein Ey is multiplied by Hz after appropriate time shifting to create a focal point. Numerical...
Electromagnetic problems for metallic nanoparitcles are analyzed by using a boundary integral equation method. Applying fast inversion of Laplace transform, time domain responses are investigated. The computational results obtained by our method are compared with FDTD or exact solutions. We verify that our proposed method is fully error controllable and suitable for solving nano-scale electromagnetic...
All optical magnetic recording with circularly polarized light has been studied for developing ultra-high speed recording. An asymmetric cross antenna, constituted by two perpendicular dipole antennas of different length, is investigated to generate localized circularly polarization in recording medium from linearly polarized incident light.
This paper presents a numerical algorithm based on the finite-difference method to simulate the electromagnetic fields generated by arbitrarily-oriented transmitter coils in a three-dimensional (3D) fully anisotropic medium. An edge-centered, staggered-grid finite-difference method is used to solve the vector equation for the scattered electric field. The resultant matrix equation is solved iteratively...
Large-scale full-wave modeling of multistatic target imaging in a rough ground environment is described. The emulation methodology employs a parallelized three-dimensional finite-difference time-domain (FDTD) algorithm in characterizing the near-grazing angle electromagnetic scattering from the ground surface and buried and on-surface targets in the form of landmines and unexploded ordnances (UXO);...
An approximate method for determining the statistical properties of an FDTD Analysis has been derived, allowing the determination of the mean and the variance of an FDTD simulation. This stochastic simulator progresses in the same fashion as an FDTD simulation progresses. The variance-wave builds and propagates with reflections occurring at dielectric boundaries. Computer overhead is reduced, i.e...
This paper presents time-domain analytic fields of a focused beam with higher-order compensations for the finite-difference time-domain (FDTD) total-field/scattered-field (TF/SF) formulation. The higher-order compensations account for the FDTD numerical dispersion and the frequency-dependent field polarizations. With these compensations, the focused beam can be excited with minimal field leakage errors...
In 2002 Anantha and Taflove proposed a generalized total-field/scattered-field (G-TFSF) formulation to facilitate the study of infinite scatterers, such as wedges [IEEE Trans. Antennas and Propagat., 50(10):1337–1349, 2002]. In the G-TFSF method, portions of the TFSF boundary are embedded in the perfectly match layer (PML) that terminates the grid. To account for the effect the PML has on the incident...
We describe the FDTD implementation of quasi-monochromatic Gaussian Schell model (GSM) beam incidence, which is frequently used to model partial coherence effects in lasers. The cross-spectral density of the GSM beam is subjected to coherent mode decomposition, and each coherent mode is simulated in a separate FDTD run using the plane-wave decomposition (or angular-spectrum) method. The output intensity...
In this paper, FDTD method combined with Overset Grid Generation method is proposed to the analysis of the EM fields around a rotating body. We have previously proposed this numerical approach for a stationary and uniformly moving body. Lorentz transformation is combined to the analysis to comprise with the high relative velocities. The results of the numerical analysis show the modulations of the...
In this paper the approach followed by Chilton et all. to develop a provably passive and stable 3D FDTD subgridding technique, is adapted to Body-Of-Revolution (BOR) FDTD. To this end a new set of basis functions is presented together with the mechanism to assemble them into an overall mesh consisting of coarse and fine mesh cells. To preserve the explicit nature of the leapfrog time stepping algorithm,...
We present unconditionally stable Non-orthogonal Locally One Dimensional (LOD) finite-difference time-domain (FDTD) method. The non-orthogonal formulation can be useful to extend the LOD-FDTD methods for curved discontinuities so as to obtain more accurate results with reduced computational resources. Formulations for CPML as well as scattered-field formulation are provided. Numerical simulations...
In the case of far filed exposure to human body, whole body resonance phenomena arise in VHF [1] frequency band when the component of E-field is parallel to the human body's height. In this phenomenon intensive induced current is observed in the human body. In this paper, in order to analyze this phenomenon with high accuracy by using FDTD method. We propose an efficient modeling method to model half...
This paper presents a new time-domain simulation scheme that incorporates magnetic materials operating in the dominant mode. The proposed scheme is a modification of the Yee scheme by incorporating the Landau-Lifschitz equation of motion including the dominant and loss terms. The proposed scheme is validated by comparison of simulated scattering parameter data with scattering parameter data obtained...
An accurate and efficient finite-difference time-domain (FDTD) method for analyzing axially symmetric structures is presented. The method achieves its accuracy and efficiency using exact absorbing conditions (EACs) for terminating the computation domain and a blocked-FFT based scheme for accelerating the computation of the temporal convolutions present in non-local EACs. The method is shown to be...
In the simplest formulation, the FDTD algorithm requires that objects follow the rectangular grid. For curved surfaces, this is a severe limitation. In this paper, an approach to modify an existing rectangular FDTD code to model structures more naturally described in another coordinate system is demonstrated. The approach is a modification to the update coefficients and does not require significant...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.