Re. wireless charging
I have some experience with this.
Evanescent wave (close range) wireless charging is wavelength dependent so at 60 kHz (used in Wii chargers) and 120 kHz (used in some Pre chargers etc) it has to be within 5" of the charge station.
The losses are a lot less but resistance loss in the coils and capacitor(s) account for a lot, as does simple inverse square law.
One option which is being explored is to use very long wave ie 2um waves which are deep infrared.
These are basically eye safe and the heat aversion response means that people can't get injured.
Also relevant, most Powerbeam-like setups basically use a solar cell as the Rx which is tuned to the exact wavelength being transmitted so the efficiency can be at least 3 times normal ie 52% and any wasted energy that is absorbed can be converted by a vacuum thermoelectric cell on the back of the panels.
These cells are in common use, last time I checked they were looking into using photonic lattice technology which works equally well for extracting and collecting light though in this case a cone like structure like a fly's eye would be more effective for collecting a diverging beam.
Yet another approach I am working on at home involves using a diamagnetic Rx coil, the idea here is that a bismuth coil electroplated with silver and nickel is a lot more effective at collecting weak electromagnetic waves than a conventional silvered copper coil and is somewhat easier to adjust, as any metallic objects
near or over the coil don't detune it thanks to the diamagnetic bismuth offsetting the effect.
AC/DC