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Microwave blackbodies for spaceborne receiversThe properties of microwave blackbody targets are explained as they apply to the calibration of spaceborne receivers. Also described are several practicable, blackbody targets used to test and calibrate receivers in the laboratory and in the thermal vacuum chamber. Problems with the precision and the accuracy of blackbody targets, and blackbody target design concepts that overcome some of the accuracy limitations present in existing target designs, are presented. The principle of the Brewster angle blackbody target is described where the blackbody is applied as a fixed-temperature test target in the laboratory and as a variable-temperature target in the thermal vacuum chamber. The reflectivity of a Brewster angle target is measured in the laboratory. From this measurement, the emissivity of the target is calculated. Radiatively cooled thermal suspensions are discussed as the coolants of blackbody targets and waveguide terminations that function as calibration devices in spaceborne receivers. Examples are given for the design of radiatively cooled thermal suspensions. Corrugated-horn antennas used to observe the cosmic background and to provide a cold-calibration source for spaceborne receivers are described.
Document ID
19850014757
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Stacey, J. M. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
September 5, 2013
Publication Date
March 1, 1985
Subject Category
Instrumentation And Photography
Report/Patent Number
JPL-PUB-85-10
NASA-CR-175647
NAS 1.26:175647
Accession Number
85N23068
Funding Number(s)
CONTRACT_GRANT: NAS7-918
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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