How Does Wireless Charging Work?

Wireless charging over the air and across the room with no wires or pads? It’s magical, simple, and brand spankin’ new. And yes, it’s happening right now. Read on to discover how wireless power works and how your company and devices may benefit from this groundbreaking technology.


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What is Wireless Charging?

At the forefront of wireless charging, there are three forms of technology: induction charging, resonant charging, and the most versatile form yet: RF-based wireless power. Induction and resonant charging have been available since the 90s, while RF-based Cota® wireless power by Ossia Inc.® debuted in the late 2000’s.

1.   Induction and Resonant charging

The electric toothbrush on your bathroom counter is kept constantly recharged via short-range induction charging. Many wearables, like mobile phones, smartwatches, and headphones are also kept powered by the simple power of induction. These devices don’t have visible wires or electrodes that touch; instead, induction charging works when the coils of wire inside the charger and device are in close enough proximity to create a magnetic field.

Although induction charging has been dubbed “wireless power,” it isn’t truly wireless because the charging base must be plugged in, thus keeping the device stationary while it is being charged. You can’t charge your electric toothbrush while you use it – thus, it doesn’t quite fit the “truly wireless” bill.

Resonant charging, on the other hand, is mid-range over-the-air charging with lower power yield. With resonant charging, the device receiving power doesn’t have to be as perfectly aligned or seated on its charger to receive power. When considering bulkier operations, like parking an electric car in a space with a charging plate in the ground, resonant charging means the car would not need to be in the *perfect* spot, but rather just in a good enough spot. Resonant charging is powered by a pairing of circuits tuned to the same resonant frequency, much like RFID cards or office badges, the in-vehicle toll transponder that helps you skip rush hour, and the robot vacuum that can’t quite park itself in the right spot every time. While this less-than-perfect aligning of devices allows for minimal power to be shared, it isn’t strong enough to reliably and efficiently charge something like a handheld retail scanner or a cell phone.

2.   Radio Frequency (RF) wireless power

Radio frequency (RF) wireless power, or “far-field” charging, charges stationary or moving devices at a great distance without requiring a direct line of sight.

Consider your Wi-Fi router in the closet sending internet to your smart TV, laptop, and kindle; the Bluetooth speaker in your living room connected to your phone in the kitchen; your three baby cameras sending video to the handheld receiver. These connections persist as long as the devices are within range, regardless of walls, pets, or your granddad standing directly in front of the television. Ossia’s Cota System functions in the same way.

Imagine the wireless functions of Wi-Fi, Bluetooth, and Cota Wireless Power in terms of “beacons”: if your device shouts, the transmitter hears the request and sends data, audio, or power your way. You don’t have to put your phone down while it’s connected to Wi-Fi or Bluetooth, and likewise, while your phone is being charged by Cota, you can keep using it.

RF-based wireless power systems like Cota can be used for virtually any electronic device, whether it was previously powered by disposable batteries or a cord plugged into the wall. Mobile phones, smartwatches, electronic shelf labels and displays, security cameras, door locks and doorbells, GPS trackers, retail scanners, biomedical devices, and IoT are just a few of the devices that can be powered wirelessly – truly wirelessly – by Cota’s RF-based power.

Cota technology is available for license today. Click here to learn more.

How does radio frequency (RF) power work?1

  1. A tiny receiver chip is embedded into an electronic device, completely replacing its batteries.
  2. A power transmitter (Cota Hub, for example) is designed to fit the environment, where it may closely resemble a Wi-Fi router or be disguised as a ceiling tile or even wall art.
  3. The receiver initiates the connection conversation by sending a beacon signal “calling out” with a request for a transmitter in range to send power.
  4. The transmitter hears the beacon and instantly sends power back to the receiver. This back-and-forth happens 100 times per second, so power provided to devices is uninterrupted even while the device is in motion.

    Cota’s back-and-forth technology holds over 230 patents and regulatory approval in over 62 countries.

  5. Since the beam of power is retrodirective, it doesn’t ever pass through people or pets. Power is sent along the exact same path as the beacon request. The most efficient path is the one the Hub, or transmitter, uses when mapping its power beam. Cota holds a two-way conversation at all times, which ensures productive energy delivery.
  6. The Cota System is managed via a cloud-based service that controls both the Hub and receivers. Power delivery can be turned on and off or scheduled ahead of time, and data on charging metrics is available for review.

1This describes the wireless power system Cota Real Wireless Power. Not all wireless power systems operate the same.

Benefits of RF-Based Wireless Power

There are three primary benefits of Cota and RF-based wireless power:

  1. Effectiveness
    Current Cota transmitters regularly broadcast an excess of 8W of power to devices over six feet away, and the efficiency of RF-based power continues to rise as this technology continues to develop.
  2. Distance
    Current reliable distances of Cota power distribution extend to 10 meters (30+ feet). That’s a football endzone!
  3. Non-line-of-sight
    Instead of hunkering your device on a charging pad for half an hour, you could have your device on the opposite side of the room of a party full of people and still receive a charge.

Click here for more information about the different types of wireless charging technologies available.

Questions about wireless charging for your electronic devices? We’re here to help. Contact for more information.

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