Application Possibilities of Passive Remote-Sensing Systems in the Millimeter-Wave Region

Passive remote sensing in the microwave and millimeter-wave region, in short "microwave radiometry," is a powerful method for environmental observation. The advantages in comparison with optical and active microwave methods, respectively, are all-weather capability, penetration depth, low power consumption, and the missing of biological and environmental impacts. This presentation gives, after a discussion of advantages and disadvantages of microwave radiometry and a short reference to the state of the art, several application possibilities based on airborne DFVLR measurements at 32 and 90 GHz: earth observation with respect to vegetation conditions, ground moisture, and snow cover; traffic control at land and sea and sensing of road conditions; and earth observation during bad ground visibility. An outlook to expectable future developments will be given on the basis of present requirements. Main goals are the increase of data rates as well as geometrical and temperature resolution improvements by use of multireceiver systems in order to get operational microwave radiometry systems for remote sensing.