Waveguide Attenuation

Waveguides can support traveling waves at frequencies higher than their cutoff frequencies. However, the traveling waves are attenuated by losses in the dielectric medium that fills a waveguide and by losses in the conducting sidewalls. Dielectric losses generally are negligible where waveguides are filed with air, but dielectric losses can exceed conduction losses if waveguides are filled with a medium other than air. The attenuation of any waveguide increases very rapidly at frequencies below cut-off, even a waveguide that has vacuum dielectric and almost perfectly-conducting walls, because no waveguide is able to support traveling waves at frequencies below cutoff. The most important single thing to know about waveguides is that they are fundamentally unable to transmit significant amounts of energy at frequencies below cutoff. ©2005 Tigertek, Inc. All rights reserved.

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