The RPG-HATPRO (G5 series) is a ground-based passive microwave radiometer, which operates in two frequency bands. It has seven channels in the K-band (22.24–31.40 GHz), for retrieving water vapor profiles, and seven channels in the V-band (51.26–58 GHz; oxygen band), for retrieving temperature profiles. The RPG-HATPRO measures brightness temperatures at a temporal resolution of up to 1 s. It has two operation modes: zenith pointing (Z-mode) and elevation scanning mode (S-mode). In the Z-mode, the Microwave radiometer points vertically, while in the S-mode it scans the atmosphere under elevation angles between about 4o and 90o.
The radiometer is designed to acquire continuous profiles of temperature and humidity across the atmosphere.
Fig 7: Microwave Radiometer