Is wireless power transmission on the horizon?

Broadcast power” is one of the holy grails of technical advancement. In the 19th century, we used wires to carry signals (think telegraph, and later, telephone). Signals are changes in electrical current (etc.) that can be interpreted meaningfully (Morse code, for example).

After the creation of electrical motors and dynamos, wires were used to carry actual power (wattage, energy) to make these motors work.

The difference between signals and power is wattage. Electrical signals can use very low power, since it’s the change in electrical current (or voltage, or whatever) that carries the meaning. But actually electrical power needs big numbers — high voltage, high wattage. At the moment, our wired world carries both — signals and power. Not so the wireless world.

The wireless world is signal-only, until now

Consider the wireless world, the world of radio, television, satellite phone, WiFi, and your “smart” device. I’ll bet you haven’t considered that, unlike the wired world, the wireless world is very low power — signal-only. You can talk on your wireless devices, or use them to listen. But you can’t power them in any meaningful way — you can’t charge their batteries wirelessly, for example.

Electricity via Shutterstock

Electricity via Shutterstock

Wouldn’t it be nice if you could power your devices wirelessly? Imagine a world entirely free of power cords. Ever since man has been able to broadcast signals, back in the radio days (at the time called the “wireless”), the ability to broadcast a great deal of power over meaningful distances as well has been a dream. And a seemingly impossible one.

In this spirit, I want to put the following on your radar. It’s highly technical in parts, but the conclusion is plain enough. These are the relevant pieces.

First, this is a way to sidestep something called the “Shannon limits” and get more from existing 5G LTE cell phone technology. If the following is too technical for you, just bear with it. The “mind-blowing implications” the writer alludes to won’t be. (As you read, keep in mind that “wireless communication” means “signal” as discussed above.)

How Steve Perlman’s “Revolutionary” Wireless Technology Works — and Why its a Bigger Deal than Anyone Realizes

Before I get into the technical evaluation of Artemis‘s demo videos and much-ballyhooed claims in the press, let’s cut through the hype:

Is this going to revolutionize wireless communications? While these demos alone don’t necessarily demonstrate speeds beyond what is theoretically capable with LTE systems today, I think the evidence is clear that this technology can offer a solution to the “spectrum crunch” problem, so I’d say yes. From a mobile consumer’s standpoint, it’ll just seem like the next step in evolution from 4G to 5G – much faster, more consistent speeds, and with lower latency. Now, whether or not it actually gets deployed by carriers is another matter all together.

Is this invention completely unique? No! Just last year, a German university demonstrated a working prototype of essentially the same technique (albeit without a snazzy streaming video demo or compatability on traditional cell phones) in the video here. The theory behind this sort of system is referred to as “network MIMO” or “cooperative MIMO” in the literature and “coordinated beamforming” in the 3GPP LTE-A specification [30], and dates back to 2001, if not earlier [1] [2]. But then again, when is an invention ever done in a vacuum? Calculus, the telephone, and the Hall-Heroult process for smelting aluminum were all discovered simultaneously. What Artemis has done is taken techniques that are being proposed for upcoming 5G systems and figured out how to solve all the engineering challenges involved, years ahead of the rest of the industry [3] [4].

Have they broken the Shannon limit? No, they’ve just side-stepped it. Each user now has their own channel, and can use it up to the full Shannon limit without having to share it with anyone else. See the section of theirwhitepaper beginning with “Shannon’s Law is not about spectrum data rate limits, it is about channel data rate limits”.

NOTE: Be sure to read the really mind-blowing implications this technology could have far beyond communication in my conclusion if you’re in a hurry.

You can read through the piece if you like. Very handsome equations put in an appearance, and if you’re halfway smart, it’s an interesting read. Just keep in mind, LTE is the latest cell phone technology.

Broadcast power is one of the implications of this work

Now that “mind-blowing” conclusion (my paragraphing and emphasis):

Overhead wires in Delhi, India (source)

Overhead wires in Delhi, India (source)

What in the world is [Perlman] talking about? “What else is radio used for besides communication?” I asked myself. Nothing, besides radio astronomy. But then I asked myself “What else could radio be used for?” and the answer became clear: wireless power transmission!

You see, while Tesla’s idea of wireless power transmission never got to fruition, using microwave beams to transfer electricity between two places within line-of-sight distance of each other is nothing new — William Brown demonstrated a wirelessly-powered helicopter using microwaves beamed from the ground back in the 60s (notice the tether in the picture, to keep the helicopter positioned in the right place) [28][29].

It was replicated recently by the BBC science show Bang Goes the Theory in their video. You just have an array of rectennas at the receiver to convert the received RF energy to DC power. But it’s never been feasible or practical for any real-world applications because:

You would need to keep steering the transmitting antenna to keep it pointed towards the receiver (which, for all the interesting applications, is mobile). Steering antennas requires either an expensive gimbal mechanism, or an even more expensive phased array. Kymeta‘s metamaterial antennas could dramatically reduce this cost, but it’s in general hard to do.

The amount of power you’re transmitting through the single antenna is far above what is considered safe, should any living being pass through the beam.

The inability to focus the microwave beam tightly means a lot of energy is wasted, and the receiver cannot be near any life forms.

But with Artemis:

You could use beamforming instead of beamsteering, eliminating the cost of traditional approaches.

The power being transmitted would be split among hundreds of antennas, each of which is individually not transmitting harmfully high levels of RF energy. At the location of the receiver constructively interferes to add up to the necessary power required, and everywhere else the radio waves just add up to noise.

The ability to focus the radio waves to a sphere of energy just a cm in diameter means potentially that little energy will be wasted, and it’s safe to use around humans (assuming the receiver itself is a cm thick).

My brain almost exploded when I realized this. While 5G is a big leap in performance from existing 4G technology, it doesn’t provide any fundamentally new capabilities to us. Wireless power, though would be a total game-changer.

And then he looks at the implications. Very plain-English, this:

What would the implications be?

Consumer electronics that never need to be plugged in again – phones, tablets, laptops, televisions could all be powered wirelessly in the home and office.

With transmission towers spaced every kilometer along major highways, electric cars would not need massive, expensive batteries. Everyone could afford a Tesla, and the demand for oil would drop.

With transmitters on a few rooftops in a city, you could have drones and quadcopters delivering groceries and mail, again without heavy batteries that limit their flying time.

You could build an electrical grid that’s a wireless mesh network, especially in developing countries, and have excess power from solar panels beamed to other locations which need it.

There are probably a slew of other ideas that I haven’t even considered – readers, please comment below!

Is there any evidence to substantiate this hypothesis?

Well, as it turns out, Perlman has filed two patents on just these ideas:

System and method for powering vehicle using radio frequency signals and feedback

System and method for powering an aircraft using radio frequency signals and feedback

And if you look at the intro video, there’s a shot of cars driving down a highway connected to pCells, which satisfies the “clue” hint he mentioned in his last slide.

OK, I’m breathless. I hope you stayed with this until now. If this technology works as described, it’s game-changing.

Broadcast power — a dream of scientists and scifi writers since the early 20th century. Are we on the verge? If so, get ready for another world-historical technical innovation.


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Gaius Publius is a professional writer living on the West Coast of the United States.

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