Fully integrated millimeter-wave radiometers: Development level and perspectives

Radiometers are sophisticated sensors commonly in use since decades in different fields, among the others: radioastronomy, meteorology and remote sensing from satellite. Being a sort of noise temperature eye, the radiometer can be applied, in principle, to a huge variety of observations, nevertheless its exploitation has been limited so far by the cost of the technology required. The most of the existing apparatuses in fact are actually based on waveguide or hybrid technology in combination with 3D antennas; it poses severe constraints in terms of cost, dimension, weight and mass production possibilities and ultimately applicablity. Nowadays, the strong increment of the operating frequencies of even low cost IC technologies, such as CMOS with cut off frequencies far beyond 100 GHz, allows us to look at radiometers from a different and wider perspective.