Well beyond the 600 MHz auction, or even the opening up of the 3.5 GHz band to tiered access, the US is hunting for new sources of spectrum for the difficult two-faced mobile model that is evolving, around ever-faster broadband combined with ever-lower latency machine-to-machine connections for the IoT. The FCC is engaged in projects focused on a range of options from satellite bands to drones to dynamic access to unlicensed or shared spectrum. And as always, the R&D labs of the vendors and operators are going several steps further than that. Google, of course, has been testing drones – as well as tethered balloons and other mechanisms – to support broader wireless broadband delivery. Earlier this year, it supported…