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Optical Engineering

Experimental analysis of diffraction by wavelength-sized metallic gratings in the microwave region
Author(s): Shakila A. Khan; Dong-Ning Qu; Ronald E. Burge
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Paper Abstract

The effects of spherical wave incidence on the microwave diffraction patterns of wavelength-sized gratings are shown and explained. These effects include broadening the angular width of each diffraction order; introducing extra phase differences between the adjacent periods; and, most significantly, inducing extra diffraction orders that would otherwise not exist were the incident wave a plane wave for the same grating. The existence of these extra diffraction orders is due to the range of angles of incidence caused by the spherical wave incidence. The diffraction patterns of wavelength-sized gratings for TE and TM polarization have very different characters. In particular, the TE specular components were saturated for an increasing depth of groove, while the TM specular components vary in a manner related to the depth-induced phase change at shallow depth; for deep-groove gratings, the TM components at backscatter were strong. It is believed that the far-field diffraction patterns are closely connected to the surface field distribution. The polarization dependence of the far-field diffraction patterns is explained in terms of the electromagnetic boundary conditions around the grooves. The strong TM components at backscatter are understood to be the result of multiple scattering.

Paper Details

Date Published: 1 December 1993
PDF: 5 pages
Opt. Eng. 32(12) doi: 10.1117/12.151290
Published in: Optical Engineering Volume 32, Issue 12
Show Author Affiliations
Shakila A. Khan, King's College London (United Kingdom)
Dong-Ning Qu, Kings College London (United Kingdom)
Ronald E. Burge, Univ. of London (United Kingdom)

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