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Waveguide modes for current approximation in frequency selective surfaces

Poulsen, Sören LU (2006) In Technical Report LUTEDX/(TEAT-7147)/1-10/(2006) TEAT-7147.
Abstract
The importance of using efficient bases for current expansion in numerical computations of electromagnetic field problems has been emphasized for several decades. It is well known that the basis functions should approximate the physical current (electric or magnetic) to some extent. Moreover, for efficiency, it is reasonably to require that only a few basis functions are needed in order to obtain adequate results. Bases for specific frequency selective surface (FSS) element geometries has frequently been suggested, however, few papers address general element geometries. In this paper we establish an efficient set of basis functions, for a general element geometry, with the finite element method (FEM). The Helmholtz' eigenvalue problem is... (More)
The importance of using efficient bases for current expansion in numerical computations of electromagnetic field problems has been emphasized for several decades. It is well known that the basis functions should approximate the physical current (electric or magnetic) to some extent. Moreover, for efficiency, it is reasonably to require that only a few basis functions are needed in order to obtain adequate results. Bases for specific frequency selective surface (FSS) element geometries has frequently been suggested, however, few papers address general element geometries. In this paper we establish an efficient set of basis functions, for a general element geometry, with the finite element method (FEM). The Helmholtz' eigenvalue problem is solved by the FEM in order to obtain the waveguide modes of a waveguide with the same cross section as the considered FSS element. The transverse electric field of the first $n$ wave\-guide modes, ordered by the size of the corresponding eigenvalues, are used for current approximation (electric or magnetic) in the method of moment (MoM) analysis of the FSS. These current modes are Fourier transformed by FFT using the zero-padding technique. Generally, it is found that only a few waveguide modes, typically 10, are required in order to obtain adequate results. It is also found that obtained results agrees very well with results obtained by Periodic Moment Method (PMM) code. (Less)
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Technical Report LUTEDX/(TEAT-7147)/1-10/(2006)
volume
TEAT-7147
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10 pages
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[Publisher information missing]
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English
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yes
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d6ae2471-0f72-4e67-bbb1-db56894b49d1 (old id 1787155)
date added to LUP
2011-02-21 09:26:00
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@techreport{d6ae2471-0f72-4e67-bbb1-db56894b49d1,
  abstract     = {The importance of using efficient bases for current expansion in numerical computations of electromagnetic field problems has been emphasized for several decades. It is well known that the basis functions should approximate the physical current (electric or magnetic) to some extent. Moreover, for efficiency, it is reasonably to require that only a few basis functions are needed in order to obtain adequate results. Bases for specific frequency selective surface (FSS) element geometries has frequently been suggested, however, few papers address general element geometries. In this paper we establish an efficient set of basis functions, for a general element geometry, with the finite element method (FEM). The Helmholtz' eigenvalue problem is solved by the FEM in order to obtain the waveguide modes of a waveguide with the same cross section as the considered FSS element. The transverse electric field of the first $n$ wave\-guide modes, ordered by the size of the corresponding eigenvalues, are used for current approximation (electric or magnetic) in the method of moment (MoM) analysis of the FSS. These current modes are Fourier transformed by FFT using the zero-padding technique. Generally, it is found that only a few waveguide modes, typically 10, are required in order to obtain adequate results. It is also found that obtained results agrees very well with results obtained by Periodic Moment Method (PMM) code.},
  author       = {Poulsen, Sören},
  institution  = {[Publisher information missing]},
  language     = {eng},
  pages        = {10},
  series       = {Technical Report LUTEDX/(TEAT-7147)/1-10/(2006)},
  title        = {Waveguide modes for current approximation in frequency selective surfaces},
  volume       = {TEAT-7147},
  year         = {2006},
}