A Quick Look to 6G Antenna Concepts as seen from the Deep Physical Layer Level

The race for the 6G has started, and new exciting ideas on 6G antennas are on the table. This contribution gives a look to the 6G ideas from a novel angle of view, the Deep Physical Layer (DPL), a layer added at the very botton level of the OSI stack, in which the analysis is carried out at the electromagnetic field level. It is suggested that the performance of the communication system can be quantified using the space-time Number of Degrees of Freedom (ST-NDF), allowing a simple comparison among the different solutions.