Infrared measurements of waveguide modes and radiation patterns of beveled-cut circular waveguide microwave aperture antennas
- Air Force Phillips Lab., Kirtland AFB, NM (United States). Microwave Research Group
An infrared (IR) imaging technique is used to measure the internal modes and the radiation pattern of a 30{degree} beveled-cut circular waveguide microwave aperture antenna. IR thermograms of the electric field distributions in several cross sections of the waveguide feed line of the antenna are measured. A thin, lossy detector screen is placed in the plane of measurement. The absorbed heat energy in the screen is re-radiated as electromagnetic (EM) ``blackbody`` energy, which is detected with an IR camera. Due to the absorbed energy, the temperature of the detector screen rises above the ambient temperature of the waveguide by an amount proportional to the local electric field intensity (energy) at each point in the screen material. The temperature distribution in the screen material is correlated to the intensity of the electric field absorbed in the screen and is presented as a false-color image of the electric field distribution. The antenna is fed with a coaxial TM{sub 01} mode, which does not radiate in the bore-sight direction of an open-ended cylindrical waveguide; therefore, a combined mode converted/radiator is used to convert the TM{sub 01} mode into the dominant circular waveguide TE{sub 11} mode, which does have a main beam radiation pattern. A 30{degree} beveled-cut radiator is used for mode conversion. The far-field radiation pattern of the beveled-end aperture antenna is also measured.
- OSTI ID:
- 220720
- Report Number(s):
- CONF-940449-; ISBN 0-8194-1549-9; TRN: IM9620%%114
- Resource Relation:
- Conference: Society of Photo-Optical Instrumentation Engineers conference on intelligent information systems, Orlando, FL (United States), 4-8 Apr 1994; Other Information: PBD: 1994; Related Information: Is Part Of Thermosense 16: An international conference on thermal sensing and imaging diagnostic applications; Snell, J.R. Jr. [ed.]; PB: 330 p.; Proceedings/SPIE, Volume 2245
- Country of Publication:
- United States
- Language:
- English
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