Sixth generation radio will operate in the $$95\text{ GHz}$$ to $$275\text{ GHz}$$ range, and will provide data rates of $$100\text{ Gbit/s}$$ [38]. While 5G hopes to provide these data rates at $$60\text{ GHz}$$ this may not come to pass as the required spectral efficiency of $$14\text{ bits/s/Hz}$$ and requires $$60\text{ GHz}$$ hardware with very high dynamic range and this is unlikely to be available for some time. With 6G these data rates will be possible with much lower-order modulation and hence reduced demands on hardware Regulatory bodies have allocated several bands in this range. In the USA these bands are $$116–123\text{ GHz},\: 174.8–182\text{ GHz},\: 185– 190\text{ GHz},$$ and $$244–246\text{ GHz}$$ for a total of $$21\text{ GHz}$$ of spectrum. Atmospheric losses can be large at these frequencies but, except for a peak of absorption around $$140\text{ GHz}$$, this is more than compensated by the pencil-like beams generated by many-element phased array antennas possible at these high frequencies. The $$100+\text{ GHz}$$ frequencies have wavelengths of $$3\text{ mm}$$ or less enabling functionality not available at $$60\text{ GHz}$$ and below. These include precise positioning with millimeter resolution, near visual-quality imaging through fog and clouds, wireless cognition (off-loading large data sets from a mobile units for fixed computation), and unique sensing modalities by exploiting the many molecular resonances that occur above $$100\text{ GHz}$$. The overwhelming challenge is the development of physical hardware and the development of array processing technologies [38].