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Proceedings Paper

Technique for designing beam-forming reflector systems based on measured amplitude and phase patterns
Author(s): B. M. Harper; Ronald J. Vernon
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Paper Abstract

Internal beam-shaping reflectors are crucial for getting high powers out of vacuum-sealed gyrotrons. Thermal limitations of the vacuum window as well as external injection of the microwave beam into corrugated waveguides require very specific beam characteristics. Previous beam shaping reflectors have achieved satisfactory results but have shown room for improvement. One cause for error has been inaccuracy in the theoretical modeling of the input to the reflectors. Small inaccuracies in the amplitude and phase distribution of the theoretical patterns for the input beam can cause dramatic effects in the output beam's characteristics. It is possible to use measured data instead of theoretical data for the input to the mirror design. Measured amplitude data of the input to the reflectors has been available; however, both the amplitude and phase information of the beam are required for the design procedure. It is difficult to directly measure the phase distribution at 110 GHz so a phase reconstruction algorithm was developed to determine the phase pattern associated with a propagating beam. The measured amplitude data with its reconstructed phase was then used as the input to the beam- shaping, dual-mirror design. In this paper we discuss the design procedure for the dual-mirror design using measured amplitude data with its reconstructed phase for the input.

Paper Details

Date Published: 13 November 1998
PDF: 4 pages
Proc. SPIE 3465, Millimeter and Submillimeter Waves IV, (13 November 1998); doi: 10.1117/12.331190
Show Author Affiliations
B. M. Harper, Univ. of Wisconsin/Madison (United States)
Ronald J. Vernon, Univ. of Wisconsin/Madison (United States)

Published in SPIE Proceedings Vol. 3465:
Millimeter and Submillimeter Waves IV
Mohammed N. Afsar, Editor(s)

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