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  • 1
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    Modeling of resistive sheets in finite element solutions (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A formulation is presented for modeling a resistive card in the context of the finite element method. The appropriate variational function is derived and for variational purposes results are presented for the scattering by metal-backed cavity loaded with a resistive card.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); 40; 6, Ju; 727-731
    Format: text
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  • 2
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    A finite element conjugate gradient FFT method for scattering (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Validated results are presented for the new 3D body of revolution finite element boundary integral code. A Fourier series expansion of the vector electric and mangnetic fields is employed to reduce the dimensionality of the system, and the exact boundary condition is employed to terminate the finite element mesh. The mesh termination boundary is chosen such that is leads to convolutional boundary operatores of low O(n) memory demand. Improvements of this code are discussed along with the proposed formulation for a full 3D implementation of the finite element boundary integral method in conjunction with a conjugate gradiant fast Fourier transformation (CGFFT) solution.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Task Reports on Developing Techniques for Scattering by 3D Composite Structures and to Generate New Solutions in Diffraction Theory Using Higher Order Boundary Conditions; 26 p
    Format: application/pdf
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  • 3
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    Modeling of resistive sheets in finite element solutions (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A formulation is presented for modeling a resistive card in the context of the finite element method. The appropriate variational function is derived and for variational purposes results are presented for the scattering by a metal-backed cavity loaded with a resistive card.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Michigan Univ., Electromagnetic Characterization of Conformal Antennas; 11 p
    Format: application/pdf
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  • 4
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    A scheme to alter the resonant frequency of the microstrip patch antenna (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Simple schemes are presented for altering the resonant frequency of a rectangular patch antenna without the need to change its size. In particular, by placing a perturbance below the patch it is shown that as much as 20 percent increase and 30 percent decrease from the resonant frequency of the unperturbed patch can be achieved. The specific configurations considered in this letter include a cavity-backed, aperture-backed, and protrusion-backed patch, and for each case design curves are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Electromagnetic Characterization of Conformal Antennas; 9 p
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  • 5
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    Electromagnetic characterization of conformal antennas (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The ultimate objective of this project is to develop a new technique which permits an accurate simulation of microstrip patch antennas or arrays with various feed, superstrate and/or substrate configurations residing in a recessed cavity whose aperture is planar, cylindrical or otherwise conformed to the substructure. The technique combines the finite element and boundary integral methods to formulate a system suitable for solution via the conjugate gradient method in conjunction with the fast Fourier transform. The final code is intended to compute both scattering and radiation patterns of the structure with an affordable memory demand. With upgraded capabilities, the four included papers examined the radar cross section (RCS), input impedance, gain, and resonant frequency of several rectangular configurations using different loading and substrate/superstrate configurations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-189530 , NAS 1.26:189530 , UMICH-027723-4-T
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  • 6
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    A finite element boundary integral formulation for radiation and scattering by cavity antennas using tetrahedral elements (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A hybrid finite element boundary integral formulation is developed using tetrahedral and/or triangular elements for discretizing the cavity and/or aperture of microstrip antenna arrays. The tetrahedral elements with edge based linear expansion functions are chosen for modeling the volume region and triangular elements are used for discretizing the aperture. The edge based expansion functions are divergenceless thus removing the requirement to introduce a penalty term and the tetrahedral elements permit greater geometrical adaptability than the rectangular bricks. The underlying theory and resulting expressions are discussed in detail together with some numerical scattering examples for comparison and demonstration.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-189491 , NAS 1.26:189491 , UMICH-028918-1-T
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  • 7
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    Edge-based finite elements and vector ABCs applied to 3D scattering (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An edge based finite element formulation with vector absorbing boundary conditions is presented for scattering by composite structures having boundaries satisfying impedance and/or transition conditions. Remarkably accurate results are obtained by placing the mesh a small fraction of a wavelength away from the scatterer.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-190352 , NAS 1.26:190352 , UMICH-025921-29-T
    Format: application/pdf
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