Without a powermeter or multimeter, that's just a gimmick demo. I've done that with UHF RFID tags from 10m away, where we harvest a few mA to light up an LED.

Without a powermeter or multimeter, that's just a gimmick demo. I've done that with UHF RFID tags from 10m away, where we harvest a few mA to light up an LED. That doesn't mean it can charge a cellphone.