Energous to Launch WattUp Distance-Charging Technology in 900 MHz Band

We found more than 50 U.S. patents and designs granted to Energous and nearly 100 patent applications still pending. The documents mostly name Chief Technology Officer Michael Leabman as prime inventor, often along with Gregory Brewer as co-inventor. Brewer is founder and CEO of the software and services company Prosoft Engineering and a former longtime Apple consultant, said his LinkedIn profile.

Though more conventional wireless-charging systems work only over short distances, with the device to be charged mounted on a mat or pad that radiates low levels of power, Energous claims in a product overview that WattUp “delivers safe wire-free charging energy at distances of up to approximately 15 feet.” WattUp technology will “continue to advance” over time in terms of “power, distance, efficiency and scale,” said the company Dec. 26 after landing FCC certification of its first-generation mid-field transmitter that sends focused, RF-based power to devices at distances up to 3 feet.

The basic principles of WattUp are explained in one of the first U.S. patents (9,124,125) granted to Energous for extended-range charging, published in two stages, September 2015 and March 2017, based on a June 2013 application by Leabman and Brewer. High-power radiation is needed to deliver useful amounts of energy to “target” devices over much longer distances than can be had from contact mats, so the required radiation needs to be tightly focused onto the target devices, to avoid hitting people or interfering with sensitive devices, the patent said. Focusing is achieved by shaping the energy into 3D “pockets” of power, it said. This is done by simultaneously transmitting multiple radio waves with different phasing, it said. Some phasing adds energy where it’s needed, while other phasing subtracts power where it’s not wanted, it said.

As an example, one wave may be transmitted at 5.7 GHz and another at 5.8 GHz. This is in the band originally reserved internationally for use with industrial, scientific and medical (ISM) equipment but now is also widely used for low-power, short-range communication devices such as cordless phones, Bluetooth links, near-field communication devices and Wi-Fi. Targeting the power pockets can be at distances ranging from an inch or two to more than “hundreds” of yards, the patent said.

An Energous U.S. patent application published this year (2017/0134686) explains in more detail practical challenges and human hazards of increasing the distance-charging range. Unlike a patent (787,412) dating to May 1900 on methods for transmitting electrical energy but with no means of targeting the power, Energous claims targeting by device tagging, such as by using Bluetooth techniques, and even audio.

The company’s various patents and applications propose targeting several different devices inside an automobile, or powering a laptop from a wall transmitter, and then using the laptop as a hub transmitter to target peripherals such as mice and headsets. Other patents suggest using sound waves to carry power for healthcare equipment, or for setting up a TV set to act as a charging station for devices around the room. One Energous patent (9,853,692) runs to 118 pages on using Bluetooth low-energy chips for device tagging and control. Other filings (2107/0187422 and 9,812,890) describe antenna chip design for close-range pad-charging.

Critics of distance-charging questioned the technology’s susceptibility to causing interference to wireless communications. In a patent application (2017/0373725) coincidentally published two days after Energous landed FCC certification for WattUp, a team of inventors from Sungkyunkwan University in South Korea fleshed out the risks of wireless power technology causing interference to communication systems.

It’s inevitable “in general” that interference will result when a “wireless power transfer apparatus uses the same frequency band as a wireless communication system such as Wi-Fi,” said the application. One solution is to make the wireless-charging system behave more like a Wi-Fi communications network and continually exchange handshake signals that check whether the communications airspace is “clear to send” so it can avoid “collisions” with wireless devices, it said.

An Energous spokeswoman responded that the WattUp “at-a-distance transmitter” that the FCC recently certified uses the 913 MHz band for the transmission of power, not 5.8 GHz in the ISM band that was described in one of the early patents. “Energous received previous FCC certification for 5.8GHz Near Field transmitters,” she said. “The recent FCC certification is for a Mid Field transmitter operating in the 900MHz band and the company has noted that the WattUp ecosystem will run in the 900MHz band for Near Field, Mid Field and Far Field solutions.”

The spokeswoman confirmed Energous recently changed its system from 5.8 GHz operation to one running at 915 MHz, which is used for low-power monitoring and location and sensing systems such as Zigbee. “WattUp will launch and operate in the 900MHz band,” because it has two main advantages over 5.8 GHz “for non-contact, charging at a distance,” she said. One advantage is that 900 MHz offers better safety on how energy is absorbed by the human body, she said.

Another advantage is that “coexistence” with other devices is improved in the 900 MHz band compared with 5.8 GHz, said the spokeswoman. Energous won't abandon innovating in the 5.8 GHz band because it “does have customer interest” in 5.8 GHz near-field, “closed-ecosystem solutions due to some unique advantages,” she said. Asked to specify how interference with other systems like Zigbee operating in the same 900 MHz band will be avoided, the spokeswoman said: “We have not publicly shared our coexistence technology/strategy.” The Zigbee Alliance is "excited to see new technologies improving consumer experiences with technology," said CEO Tobin Richardson Monday. "We expect that as new companies find their way into unlicensed and global bands (mainly 2.4GHz), that they will look to open standards organizations like the Zigbee Alliance.”