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- Andersson, Tommy
(författare)
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Method of moments and the use of multipole expansion
- 1991
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Ingår i: Journal Electromagnetic Waves and Applications. - 1569-3937. ; 5:11, s. 1237-1257
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Tidskriftsartikel (refereegranskat)abstract
- In electromagnetic boundary value problems integral equations involving the free space Green function for the Helmholtz equation often occur. Using the method of moments to numerically solve such an equation a matrix equation is obtained. The entries of the matrix are given as multidimensional integrals which in general have to be calculated numerically. This paper presents an efficient method to approximate the main Part of these integrals. The free space Green function is expanded in scalar spherical wave functions. The translation properties of these wave functions then imply that the matrix elements can be expressed as a series of multipole moments. The method is illustrated by an implementation in the static case and the computation of the capacitance of a square plate. Basis functions with the correct edge and corner behaviour are used. The calculations of the multipole moments are done analytically. Numerical results using the point-matching and Galerkin's method are presented.
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| 4. |
- Andersson, Tommy
(författare)
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Moment-method calculations of scattering by a square plate using singular basis functions and multipole expansions
- 1993
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Ingår i: Journal Electromagnetic Waves and Applications. - 1569-3937. ; 7:1, s. 93-121
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Tidskriftsartikel (refereegranskat)abstract
- The method of moments is used to solve electromagenetic boundary value problems numerically. It is known that the choice of basis functions is crucial for the numerical efficiency. Fast convergence is achieved provided the basis functions efficiently approximate the unknown function. In this paper the far field (incl. RCS) of a thin square conducting plate is calculated. Basis functions with correct edge and corner singularities are shown to greatly enhance the convergence compared to ordinary "rooftop" functions. The calculations of the matrix elements as well as the right side of the matrix equation and the scattered field are simplified by the use of a multipole technique.
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| 5. |
- Andersson, Tommy
(författare)
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Moment-method calculations of scattering by a square plate using singular basis functions and multipole expansions
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The method of moments is used to solve electromagenetic boundary value problems numerically. It is known that the choice of basis functions is crucial for the numerical efficiency. Fast convergence is achieved provided the basis functions efficiently approximate the unknown function. In this paper the far field (incl. RCS) of a thin square conducting plate is calculated. Basis functions with correct edge and corner singularities are shown to greatly enhance the convergence compared to ordinary "rooftop" functions. The calculations of the matrix elements as well as the right side of the matrix equation and the scattered field are simplified by the use of a multipole technique.
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| 6. |
- Andersson, Tommy
(författare)
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Moment-method calculations on apertures using basis singular functions
- 1993
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X. ; 41:12, s. 16-1709
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Tidskriftsartikel (refereegranskat)abstract
- The transmission properties of perforated perfectly conducting screens are of practical interest. The treatment of nonperiodical structures by numerical techniques, such as the method of moments, is very computer intensive. In this paper it is shown that using basis functions that incorporate the edge as well as the corner singularities, the number of unknowns can be drastically reduced. The advantages and limitations of the method are discussed. Numerical results are presented illustrating the transmission properties of arrays of square and rectangular apertures
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| 7. |
- Andersson, Tommy
(författare)
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Moment-method calculations on multiple apertures using singular basis functions
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The transmission properties of perforated perfectly conducting screens are of practical interest. The treatment of non-periodical structures by numerical tecniques, such as the method of moments, is very computer intensive. In this paper it is shown that using well adapted basis functions, the number of unknowns can be drastically reduced. Advantages and limitations of the method are discussed. Numerical results illustrating transmission properties of arrays of square and rectangular apertures.
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