Increasing wireless powered systems efficiency by combining WPT and Electromagnetic Energy Harvesting

This paper proposes and discusses a multiband RF-to-DC converter approach that is simultaneous fed from electromagnetic energy that is available in the ambient, at different frequencies bands, and a dedicated wireless power transmission link. The work uses narrow band matching allowing easy high efficiency conversion on its main power source, which is the WPT link. Its performance is evaluated showing an experimental peak efficiency over 40% for all frequency bands with central frequencies at 791, 1570 and 2340 MHz (with 35% efficiency bandwidth of 30, 60 and 40 MHz, respectively), when fed with a -10 dBm CW signal. Moreover, it is shown that the additional electromagnetic energy harvested will boost the efficiency of the wireless power transmission link alone from 41% up to 48%, when a collectable ambient energy of 10 μWatts is available.