Amid rumors that Apple is working on extended range wireless charging capabilities for future iPhones, there has been some speculation that Apple has partnered with Energous to implement the technology. Energous is the company behind WattUp, an emerging wireless charging technology that uses radio frequencies to charge devices from up to 15 feet away.

Though there's no concrete proof of a relationship between Energous and Apple, a new research report from Louis Basenese of Disruptive Tech Research highlights a large pool of circumstantial evidence pointing towards a potential partnership, so it's worth taking a look at Energous's technology, both in that context and as an example of the wireless charging techniques that are currently being pursued by tech companies.

Basenese posits Apple is working with a partner rather than developing an in-house solution due to the small number of patents the company has filed surrounding wireless charging -- just five, with none filed since 2013. As evidence that partner is Energous, he points towards their common manufacturing partners (TSMC and Foxconn), their membership in ANSI working towards standards for wireless power transfer compliance testing, and most notably, the fact that Energous's RF-based wireless charging system is the only long-distance solution nearly ready to launch.

From that list, we can easily eliminate HP and Hitachi, as they don't make phones. Since Samsung makes its own chips and WATT is working with TSM, we can cross it off the list, leaving only Apple and Microsoft. In reality, though, Microsoft is an also-ran in the mobile phone market and rumored to be exiting it. So we're left with one company. Of course, the identity will remain a mystery, as AAPL's notorious about insisting on secrecy with partners and employees.

In early 2015, Energous also inked a deal with an unnamed consumer electronics company, positioned as one of the top five companies in the world. Names weren't mentioned, but that's a short list -- Apple, Samsung, HP, Microsoft, and Hitachi. Basenese believes Apple is the likeliest partner by process of elimination.

Wireless charging capabilities have been implemented into several smartphones, including those from Apple's direct competitors, but Apple executives have downplayed wireless charging in the past due to its dependence on built-in chips, mats, and close proximity. In a 2012 interview, Apple marketing chief Phil Schiller said it wasn't clear "how much convenience" magnetic induction and resonance wireless charging systems offered because they still need to be plugged into the wall.



Extended range wireless charging solutions like the one Bloomberg recently suggested Apple was pursuing eliminate the need for an iPhone or iPad to be placed on a mat or near a charging source to be able to charge. Energous's WattUp transmitters, for example, can charge devices located up to 15 feet away and can charge up to 12 devices at one time, from smartphones and tablets to wearables.

WattUp is able to charge any battery-operated device that requires less than 10 watts using a technique that Energous likens to Wi-Fi. A WattUp Power Router (aka a transmitter) emits energy using a radio frequency signal delivered by miniature antenna arrays and custom control chips. Devices with a WattUp receiver (consisting of multiple miniature antennas) are then able to convert that RF signal into battery power.

While there are other distance charging solutions available that Apple could use, as Basenese points out, many of these will not be ready to launch at Apple's prospective 2017 launch timeline. Ossia is developing a similar RF-based product called Cota , but a development kit won't be available until the end of 2016 and it will be multiple years before it's ready for wide-range adoption.

Ossia's Cota transmitter on left, chip that goes in a device on right

uBeam, a company that claims to be working on wireless charging via ultrasound remains in the early prototyping stages and there are questions on whether the technology is sound, and laser-based distance charging solutions from Wi-Charge and LaserMotive remain in the prototyping stages with the latter not designed for smartphones.

Wi-Charge conceptual image

Radio frequency distance charging appears to be one of the wireless charging techniques that's the furthest along in development, making it a likely candidate for inclusion in a future iPhone. Of course, Apple could have something entirely different under development behind the closed doors of its secret lab in Cupertino, so a potential partnership with Energous, while possible, is still just speculation until more concrete proof emerges.

Even if Apple is working on an in-house solution, something similar in design to Energous' WattUp technology could be representative of how such a system would work in the iPhone.

Apple has not yet committed to implementing wireless charging in future iOS devices, as there are technical hurdles to overcome, such as the power loss that occurs when charging over distance. A signal that goes through the air experiences some drop off as a device gets further away, so an iPhone five feet from a transmitter will charge faster than an iPhone 10 feet from the same transmitter.

A newly announced keychain-sized WattUp transmitter that's portable and cost effective. Image via Digital Trends.

Wireless charging via radio frequency is also not as quick as charging with a Lightning cable, but that may not be an issue when devices can be charged continually over the air, even when in use. There are also issues with the number of devices that can be charged at once -- adding more devices to the WattUp system, for example, slows the rate at which they charge.

If Apple can eliminate these problems, current rumors suggest wireless charging technology could be implemented in 2017, perhaps in the devices that will follow the 2016 iPhone 7 and iPhone 7 Plus. This also lines up with Energous's prospective launch timeline, with the company previously stating WattUp will be available in devices starting at the end of 2016 or early 2017.