RF-Powered Wireless Sensors

The slide show here was presented by Charlie Greene of Powercast during the 4th Annual Energy Harvesting Workshop at Virginia Tech in January 2009.

Notice on slide 9 how multiple transmitters of lower aggregate power create a more even field of available RF energy than a single, higher power transmitter.  With this kind of design, a wireless power infrastructure can be created within buildings similar to lighting or Wi-Fi.  Also notice on slide 15 the graphed results of calculations that show how wireless sensors spend a majority of battery energy on sleep mode.  If power was sent wirelessly on a scheduled or periodic basis, sleep mode could be replaced by an inactive state where the sensor is essentially consuming no power.