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  • 1
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    Finite difference time domain calculations of antenna mutual coupling (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Finite Difference Time Domain (FDTD) technique has been applied to a wide variety of electromagnetic analysis problems, including shielding and scattering. However, the method has not been extensively applied to antennas. In this short paper calculations of self and mutual admittances between wire antennas are made using FDTD and compared with results obtained using the Method of Moments. The agreement is quite good, indicating the possibilities for FDTD application to antenna impedance and coupling.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 15 p
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  • 2
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    Finite difference time domain calculation of transients in antennas with nonlinear loads (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: In this paper transient fields for antennas with more general geometries are calculated directly using Finite Difference Time Domain methods. In each FDTD cell which contains a nonlinear load, a nonlinear equation is solved at each time step. As a test case the transient current in a long dipole antenna with a nonlinear load excited by a pulsed plane wave is computed using this approach. The results agree well with both calculated and measured results previously published. The approach given here extends the applicability of the FDTD method to problems involving scattering from targets including nonlinear loads and materials, and to coupling between antennas containing nonlinear loads. It may also be extended to propagation through nonlinear materials.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 16 p
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  • 3
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    FDTD modeling of thin impedance sheets (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Thin sheets of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such sheets is simplified by using sheet impedances. In this paper it is shown that sheet impedances can be modeled easily and accurately using Finite Difference Time Domain (FDTD) methods.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 17 p
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  • 4
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    Conical cut radar cross section calculations for a thin, perfectly conducting plate (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Radar Cross Section (RCS) calculations for flat, perfectly conducting plates are readily available through the use of conventional frequency domain techniques such as the Method of Moments. However, if time domain scattering or wideband frequency domain results are desired, then the Finite Difference Time Domain (FDTD) technique is a suitable choice. In this paper, we present the application of the Finite Difference Time Domain (FDTD) technique to the problem of electromagnetic scattering and RCS calculations from a thin, perfectly conducting plate for a conical cut in the scattering angle phi. RCS calculations versus angle phi will be presented and discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 13 p
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  • 5
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    Time domain scattering and radar cross section calculations for a thin, coated perfectly conducting plate (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Radar cross section (RCS) calculations for flat, perfectly conducting plates are readily available through the use of conventional frequency domain techniques such as the Method of Moments (MOM). However, if the plate is covered with a dielectric material that is relatively thick in comparison with the wavelength in the material, these frequency domain techniques become increasingly difficult to apply. We present the application of the Finite Difference Time Domain (FDTD) Technique to the problem of electromagnetic scattering and RCS calculations from a thin, perfectly conducting plate that is coated with a thick layer of lossless dielectric material. Both time domain and RCS calculations are presented and disclosed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 10 p
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  • 6
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    Wideband finite difference time domain implementation of surface impedance boundary conditions for good conductors (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media, throughout the solution volume. A 1-D implementation for a surface impedance boundary condition for good conductors in the Finite Difference Time Domain (FDTD) technique.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 4 p
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  • 7
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    A two-dimensional time domain near zone to far zone transformation (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: In a previous paper, a time domain transformation useful for extrapolating 3-D near zone finite difference time domain (FDTD) results to the far zone was presented. In this paper, the corresponding 2-D transform is outlined. While the 3-D transformation produced a physically observable far zone time domain field, this is not convenient to do directly in 2-D, since a convolution would be required. However, a representative 2-D far zone time domain result can be obtained directly. This result can then be transformed to the frequency domain using a Fast Fourier Transform, corrected with a simple multiplicative factor, and used, for example, to calculate the complex wideband scattering width of a target. If an actual time domain far zone result is required it can be obtained by inverse Fourier transform of the final frequency domain result.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; p 24
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  • 8
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    User's manual for two dimensional FDTD version TEA and TMA codes for scattering from frequency-independent dielectic materials (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Versions TEA and TMA are two dimensional numerical electromagnetic scattering codes based upon the Finite Difference Time Domain Technique (FDTD) first proposed by Yee in 1966. The supplied version of the codes are two versions of our current two dimensional FDTD code set. This manual provides a description of the codes and corresponding results for the default scattering problem. The manual is organized into eleven sections: introduction, Version TEA and TMA code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include files (TEACOM.FOR TMACOM.FOR), a section briefly discussing scattering width computations, a section discussing the scattering results, a sample problem set section, a new problem checklist, references and figure titles.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 19 p
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  • 9
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    Finite difference time domain implementation of surface impedance boundary conditions (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media throughout the solution volume. The standard approach is to approximate the surface impedance over a very small bandwidth by its value at the center frequency, and then use that result in the boundary condition. Two implementations of the surface impedance boundary condition are presented. One implementation is a constant surface impedance boundary condition and the other is a dispersive surface impedance boundary condition that is applicable over a very large frequency bandwidth and over a large range of conductivities. Frequency domain results are presented in one dimension for two conductivity values and are compared with exact results. Scattering width results from an infinite square cylinder are presented as a 2-D demonstration. Extensions to 3-D should be straightforward.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 30 p
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  • 10
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    User's manual for three dimensional FDTD version D code for scattering from frequency-dependent dielectric and magnetic materials (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version D is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into fourteen sections: introduction, description of the FDTD method, operation, resource requirements, Version D code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMOND.FOR), a section briefly discussing Radar Cross Section (RCS) computations, a section discussing some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Finite Difference Time Domain Electromagnetic Scattering from Frequency-Dependent Lossy Materials; 45 p
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