Calibration Method for Full Polarimetric Microwave Radiometers

摘要

A technique for absolute end-to-end calibration of a fully polarimetric microwave radiometer is presented. The technique is based on the tri-polarimetric calibration technique of Gasiewski and Kunkee but extended to provide a means of calibrating all four Stokes parameters. The extension is based around the use of a biaxial phase-retarding microwave plate to provide a precisely known fourth Stokes signal from the Gasiewski-Kunkee (GK) linearly polarized standard. We present the relations needed to determine the Stokes vector produced by the augmented standard, and discuss the effects of non-idealities in the various components. We illustrate the application of the extended standard to determining the complete set of radiometer constants (the calibration matrix elements) for the NOAA Polarimetric Scanning Radiometer (PSR) in a laboratory environment. A calibration matrix inversion technique and error analysis is described.