Uncertainty of Radiometer Calibration Loads and Its Impact on Radiometric Measurements



: Matti Kaisti, Miikka Altti, and Torsti Poutanen

Publisher: IEEE

: 2014

: IEEE Transactions on Microwave Theory and Techniques

: MTT

: 62

: 10

: 2435

: 2446

: 12

: 0018-9480

DOI: https://doi.org/10.1109/TMTT.2014.2349873

: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6895175

: https://research.utu.fi/converis/portal/detail/Publication/1993438



We present an uncertainty analysis of radiometer calibration.

The procedure can be used to determine the uncertainty

in the nominal brightness temperature of the unknown scene. A

total power radiometer requires frequent calibration with known

reference loads that are connected to the radiometer. Our analysis

includes uncertainties from the radiometer calibration loads and

from the connecting network (CN) that is required to multiplex

calibration loads and scene to the radiometer input. We show the

design and analysis of three calibration loads and how their uncertainties

propagate from load terminals to the radiometer calibration

plane and to the scene. All three loads, including a cryogenic

load, are simple, inexpensive, and show great stability and

accuracy. We give an uncertainty calculation example for our three

calibration loads and for the CN. We validate our model and the

long-term stability of the loads through measurements. The analysis

is done at 52 GHz, but the analysis and the construction of the

loads are generic and easily scalable to other frequencies.

Last updated on 2024-26-11 at 17:32