I wonder how it targets the signal at the device to produce that efficiency. 2.45GHz is at the upper end of Wi-Fi (channel 8 / 9), so if they can do this for wireless charging, in theory it could be done for Wi-Fi signals also, so multiple devices can operate without sharing the bandwidth as each would have its own RF beam.
On the other hand, the 70% efficiency does make me wonder where the losses are. For example, if this is due to 30% of the energy flying past the device, I don't think I would want to be holding it up to my ear, considering microwave ovens also operate at 2.45GHz. :eek: