HACKER Q&A
📣 davidajackson

Is long range 'wireless power' feasible?


I've just recently become aware of a few companies pursuing long range 'wireless power'. I only have a very basic physics understanding of it -- IIRC magnetic field strength, which I assume is what's being used (like wireless iPhone, toothbrush chargers), is inversely proportional to distance (1/r). Does anyone have any numbers on how this actually makes sense as a long range power source? If multiple sources were using long range 'wireless power', wouldn't the magnetic fields become non-uniform (non circular) and therefore mess it all up. How is this a feasible infrastructure solution? I have only a basic understanding of this concept from classical physics, so this question might be naive.

  👤 gus_massa Accepted Answer ✓
You can use a laser to transmit power wirelessly, or microwaves https://en.wikipedia.org/wiki/Wireless_power_transfer#Far-fi...

It's possible to use directed antenas to give more power to some areas, and less for others, but it's not easy.

All I've read so far to charge your cell phone in the table from a smart device in the ceiling is between dubious science and obvious scam.

Anyway, I'd be very nervous to walk across the beam of a high power wireless transmitter.

And a high power beam from the ceiling to charge the cell in your pocket? They will never convince me to try it.

👤 simonblack
Easy answer is to the question is 'No.'

However under a few very limited conditions short-range wireless power is feasible.

The problem with long-range stuff is that power falls off with the CUBE of the distance. Eventually the proportion of power that actually makes it to the receiver is a negligibly tiny amount. All of the rest is wasted.