Electromagnetic Scattering from Impedance Strips and Impedance-Loaded Conducting Strips

Electromagnetic Scattering from Impedance Strips and Impedance-Loaded Conducting Strips

Author: Marck C. Heaton

Publisher:

Published: 1990

Total Pages: 0

ISBN-13:

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This paper investigates the scattering from impedance strips and impedance-loaded conducting strips. The UTd diffraction coefficient for an edge in a conductor is heuristically modified for impedance edges and junctions. Essentially, this is done by scaling the UTD diffraction coefficients according to changes in the geometrical optics field. The new diffraction coefficients are then used to investigate the scattering from impedance strips and impedance- loaded conducting strips. Both uniform and tapered impedances are considered. Results are compared to moment method and physical optics predictions and to measured data. The scattering pattern of a uniform impedance strip was seen to behave as that for a conducting strip, but at a lower level. However, tapering the impedance was seen to significantly decrease the sidelobe levels relative to the main lobe. Also, applying an impedance load to a conducting strip reduced the sidelobe levels. This was most pronounced for loads of tapered impedance. the modified UTD approach accurately predicted the sidelobe levels and locations for the simple impedance strips, and worked fairly well for the impedance-loaded conducting strips. The predictions for all geometries were better near broadside incidence than near edge-on.


Electromagnetic Scattering from Impedance Strips and Impedance-Loaded Conducting Strips

Electromagnetic Scattering from Impedance Strips and Impedance-Loaded Conducting Strips

Author: Marck C. Heaton

Publisher:

Published: 1990

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

This paper investigates the scattering from impedance strips and impedance-loaded conducting strips. The UTd diffraction coefficient for an edge in a conductor is heuristically modified for impedance edges and junctions. Essentially, this is done by scaling the UTD diffraction coefficients according to changes in the geometrical optics field. The new diffraction coefficients are then used to investigate the scattering from impedance strips and impedance- loaded conducting strips. Both uniform and tapered impedances are considered. Results are compared to moment method and physical optics predictions and to measured data. The scattering pattern of a uniform impedance strip was seen to behave as that for a conducting strip, but at a lower level. However, tapering the impedance was seen to significantly decrease the sidelobe levels relative to the main lobe. Also, applying an impedance load to a conducting strip reduced the sidelobe levels. This was most pronounced for loads of tapered impedance. the modified UTD approach accurately predicted the sidelobe levels and locations for the simple impedance strips, and worked fairly well for the impedance-loaded conducting strips. The predictions for all geometries were better near broadside incidence than near edge-on.


Control of Electromagnetic Scattering by Antenna Impedance Loading

Control of Electromagnetic Scattering by Antenna Impedance Loading

Author: Shi-chuan Lee

Publisher:

Published: 1974

Total Pages: 88

ISBN-13:

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The application of impedance loading techniques for the reduction of backscatter from radar targets were studied. The hybrid methods which combine the GTD and the moment method were used to analyze the backscattering from various geometries such as impedance loaded infinite wedge and a two-dimensional wing model. The effect of both the trailing and the leading edge was considered by using a two-dimensional wing model. The edge diffraction source can be considerably reduced over a 3:1 frequency band for the two-dimensional case. The square plate with a loaded slot was analyzed by a wire grid model. The backscatter reduction of the square plate can be achieved at least over a 2:1 frequency band.


Control of Electromagnetic Scattering from Wing Profiles by Impedance Loading

Control of Electromagnetic Scattering from Wing Profiles by Impedance Loading

Author: J. A. Aas

Publisher:

Published: 1975

Total Pages: 108

ISBN-13:

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A computational technique has been developed to calculate the electromagnetic scattering from two-dimensional wing profiles loaded by impedance strips. These strips are represented by impedance boundary conditions. This report deals with the parallel electric polarization (TM polarization) while a similar study of the perpendicular polarization is contained in Reference (1). The effect of the impedance loading is studied for different shapes and sizes of the wing, and for different angles of incidence. The last part of the report deals with the relation between two- and three-dimensional scattering. Three-dimensional problems may in certain cases be solved at least approximately from the knowledge of the scattered field in two-dimensional problems. (Author).