Reflectivity Study of Microwave Blackbody Targets

Published

September 1, 2011

Author(s)

Dazhen Gu, Derek A. Houtz, James P. Randa, Dave K. Walker

Abstract

We report on the characterization of blackbody target reflections as part of the recent progress on the development of brightness temperature standards for microwave remote sensing at the National Institute of Standards and Technology (NIST). The very low reflections from the blackbody targets used in airborne or satellite remote sensing systems present challenges to the extraction of reflection coefficients from the measurements. A full calibration technique is developed for this study by use of a flat aluminum plate made as a known standard in combination with measurements of the empty anechoic chamber. The theoretical basis and measurement procedures, along with uncertainty analysis, are presented. Calibration results validate the method by showing its independence from measurement hardware and conditions. A comparison between the theoretical prediction of reflection coefficients of a free-standing dielectric slab with traceable physical parameters and the de-embedded reflection coefficients from experiments confirms good calibration accuracy. The specific blackbody target used in this study shows well matched properties with a power reflectivity below -40 dB over the entire measurement band (18 GHz to 26 GHz).

Citation

IEEE Geoscience and Remote Sensing Letters

Volume

49

Pub Type

Journals

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Keywords

Anechoic chamber, blackbody target, free space calibration, reflection measurement, uncertainty analysis.

Citation

Gu, D. , Houtz, D. , Randa, J. and Walker, D. (2011), Reflectivity Study of Microwave Blackbody Targets, IEEE Geoscience and Remote Sensing Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=907340 (Accessed March 13, 2025)