As noted above, much of the early-stage research towards ‘6G’ communications focuses on how usable and affordable ways could be found for radios to use spectrum above 100 GHz, known as terahertz. Much of the work is being done in the USA, east Asia and Finland, but France is getting in on the act too, as if to remind us of that country’s key role in early mobile standards. The French technology research institute CEA-Leti recently demonstrated a radio transmission that reached speeds of 100Gbps in the 140 GHz spectrum band, using a simple mixed-signal RF architecture. The spectrum used falls in the ‘D-band’ between 110 GHz and 170 GHz, which is central to the idea of terahertz or 6G…