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 applicability. 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. This contribution will show how, working with suitable architectures in combination with state of art technologies, it is possible to foresee overall radiometer performance compatible with many interesting and not yet experienced applications. Details about possible architectures will be described, present technological limits will be discussed and their influence to the performance attainable in relation with present available technologies will be treated as well. A forecast of future applications opened by new generation integrated radiometers will be discussed intended to stimulate fertile discussions.