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- Persson, Kristin, et al.
(author)
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Radome diagnostics - source reconstruction of phase objects with an equivalent currents approach
- 2012
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Reports (other academic/artistic)abstract
- Radome diagnostics are acquired in the design process, the delivery control and in performance verification of repaired and newly developed radomes. A measured near or far field may indicate deviations, e.g., increased side lobe levels, but the origin of the flaws are not revealed. In this paper, radome diagnostic is performed by visualizing equivalent currents on a radome surface. We localize phase shifts, an effective insertion phase delay (IPD), caused by patches of dielectric tape attached to a radome surface. The IPD of one layer tape, 0.15 mm, is detected. Imaging results from three different far-field measurement series at 10 GHz are presented. The measured far field is related to the equivalent surface currents on the radome surface by using a surface integral representation together with the extinction theorem. The problem is solved by a body of revolution method of moment (MoM) code utilizing a singular value decomposition (SVD) for regularization.
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- Persson, Kristin, et al.
(author)
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Reconstruction of equivalent currents using a near-field data transformation - with radome applications
- 2004
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Reports (other academic/artistic)abstract
- Knowledge of the current distribution on a radome can be used to improve radome design, detect manufacturing errors, and to verify numerical simulations. In this paper, the transformation from near-field data to its equivalent current distribution on a surface, i.e., the radome, is analyzed. The transformation is based on the surface integral representation that relates the equivalent currents to the near-field data. The presence of axial symmetry enables usage of the fast Fourier transform (FFT) to reduce the computational complexity. Furthermore, the problem is regularized using the singular value decomposition (SVD). Both synthetic and measured data are used to verify the method. The quantity of data is vast since the height of the radome corresponds to 29 − 43wavelengths in the frequency interval 8.0 − 12.0 GHz. It is shown that the method gives an accurate description of the field radiated from an antenna, on a surface enclosing it. Moreover, defects on the radome, not localized in the measured near field, are focused and detectable on the radome surface.
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- Persson, Kristin, et al.
(author)
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Reconstruction of Equivalent currents Using the Scalar Surface Integral Representation
- 2005
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Reports (other academic/artistic)abstract
- Knowledge of the current distribution on a radome can be used to improve radome design, detect manufacturing errors, and to verify numerical simulations. In this paper, the transformation from near-field data to its equivalent current distribution on a surface of arbitrary material, i.e., the radome, is analyzed. The transformation is based on the scalar surface integral representation that relates the equivalent currents to the near-field data. The presence of axial symmetry enables usage of the fast Fourier transform (FFT) to reduce the computational complexity. Furthermore, the problem is regularized using the singular value decomposition (SVD). Both synthetic and measured data are used to verify the method. The quantity of data is large since the height of the radome corresponds to 29 − 43wavelengths in the frequency interval 8.0 − 12.0GHz. It is shown that the method gives an accurate description of the field radiated from an antenna, on a surface enclosing it. Moreover, disturbances introduced by copper plates attached to the radome surface, not localized in the measured near field, are focused and detectable in the equivalent currents. The method also enables us to determine the phase shift of the field due to the passage of the radome, cf. the insertion phase delay.
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