FCC gives approval to RF power transmitter
Powercast plays in the wireless power space, but has a different twist from the more common wireless charging application that the Wireless Charging Consortium (WPC) is pushing towards standardization. Rather than charging a battery for a consumer electronics device, Powercast makes RF receiver and transmitter modules that can beam operating power to wireless sensor devices.
A poster-child application for RF power transmission currently is the penguin exhibit at the Pittsburgh Zoo that required a temperature- and humidity-monitoring network. Penguin exhibits are cold and wet and generally don’t have wall power outlets available; Bringing power or data cables wasn’t practical. The zoo originally set up the sensor network with alkaline batteries to power the nodes, but the batteries wore out quickly. Powercast retrofitted the nodes with its receivers and power circuits and placed a Powercaster transmitter with a patch antenna on the ceiling of the exhibit about 30 feet away from the receivers. Every two minutes, a pulse from the transmitter wakes up the sensor nodes, which reply with temperature, humidity, and state-of-charge information. They then return to a sleep state. They continuously charge from the transmitted RF power, however, keeping the rechargeable alkaline batteries at a constant 3V.
The company just received FCC (Part15) approval for the TX91501 transmitter module, which is available in 1-watt ($235) and 3-watt ($300) versions.
Note that you’re not going to run a hair dryer off of RF power: The system delivers power in the micro- to low milliWatts, enough to trickle charge a small battery but usually not enough to power a system directly. If you’re wondering if this amount of power will work for your applications, check out the power calculator you can download at the Powercast website.
Energy literate commented:
A total and unnecessary waste of valuable and limited resources.....coal and gasoline. These devices will never produce (or carry) the energy equivalent of coal and oil burned to make them. Furthermore, try this: pull up their power calculator spreadsheet. With default values in there, you get 159 uW at load from 3W transmitted. The efficiency of power transfer is almost nonexistant at .005%. Similar story with electric cars. The only thing green about most "green" stuff is the money being wasted. Money wasted is oil wasted, and you never get that back.
Oldskool commented:
Sounds like Tesla's work, many moons ago. We are not discovering anything.
William Ketel commented:
I also wonder about how much power is transmitted, if 1 watt is picked up. I also find it very interesting that nobody has asked what that level of electrical field is doing to the penguins, and the folks outside the windows looking at them. It is also a fact that an electrical field only 1000 times stronger can cook my meals in a microwave oven. Of course, my oven directs most of it's energy into the target,(my supper), so the comparison may not be identical. One other thing is that for sensor level instrumentation wiring, the NEC does not mandate conduits and cables. In fact, the entire system could easily use one coaxial cable for power and data. That is not new tecnology by any means.
Peter Kay commented:
Do you know if they use any antenna gain, or resonant coupling to get better efficiency? Or is most of the radiated power "wasted"? Without looking up their patents, their FAQ was not detailed enough to answer.
Powercast commented:
Wireless power based on RF energy is an innovative step forward for micro-power applications, and shares the publicly-available, unlicensed spectrum with a wide range of devices. Whether the spectrum is used for data or power (Powercast does both), consumers and industry benefit greatly from devices that are untethered and mobile (e.g. phones, WiFi, Bluetooth). Wiring may be appropriate for many applications, but the use of wiring also comes with the expense of running wires. In commercial and industrial applications this includes electricians, conduit, and facility drawings. Batteries are another alternative, but limit wide-scale wireless sensor deployment since they have to be repeatedly replaced. RF-based wireless power is an enabling green technology that reduces costs, provides freedom of placement, and allows devices to be perpetually-powered or remotely charged.
Alan commented:
A total and unnecessary waste of a valuable and limited resource.....the radio spectrum. You could buy an awful lot of wire for $300 even at today's copper prices !!
