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Normal modes in an overmoded circular waveguide coated with lossy materialThe normal modes in an overmoded waveguide coated with a lossy material are analyzed, particularly for their attenuation properties as a function of coating material, layer thickness, and frequency. When the coating material is not too lossy, the low-order modes are highly attenuated even with a thin layer of coating. This coated guide serves as a mode suppressor of the low-order modes, which can be particularly useful for reducing the radar cross section (RCS) of a cavity structure such as a jet inlet. When the coating material is very lossy, low-order modes fall into two distinct groups: highly and lowly attenuated modes. However, as a/lambda (a = radius of the cylinder; lambda = the free-space wavelength) increases, the separation between these two groups becomes less distinctive. The attenuation constants of most of the low-order modes become small, and decrease as a function of lambda sup 2/a sup 3.
Document ID
19850027007
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Lee, C. S. (Illinois Univ. Urbana, IL, United States)
Lee, S. W. (Illinois Univ. Urbana, IL, United States)
Chuang, S. L. (Illinois Univ. Urbana, IL, United States)
Date Acquired
September 5, 2013
Publication Date
September 1, 1985
Subject Category
Communications And Radar
Report/Patent Number
NASA-CR-176186
TR-85-8
NAS 1.26:176186
Accession Number
85N35320
Funding Number(s)
CONTRACT_GRANT: NAG3-475
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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