Nonlinear Radiometer Counts to Antenna Temperature Inverse Transfer Function for a Dicke Radiometer with Noise Injection

This paper presents results of a radiometric calibration of the L-band Microwave Radiometer. A forward radiometer nonlinear transfer function was derived to calibrate a 4-state Dicke radiometer utilizing empirical physical temperatures and radiometer output (counts) measurements, namely: T
_o
(ambient physical temperature), T
_scene
(noise temperature of antenna load), Co (counts for reference state), Ca (counts for antenna state), CoN (counts for reference + noise state), and CaN (counts for antenna + noise). An inverse radiometer model was developed and used in a direct comparisons of measured and modeled scene brightness temperatures during a 10-hour laboratory test. Results are presented that demonstrate superior radiometric calibration accuracy.