Experimental Verification of Wireless Power Transfer Ability to Sustain the Operation of LoRaWAN Based Wireless Sensor Node

Possibilities of far field wireless power transfer (WPT) for creation of energy autonomous sensor nodes employing LoRaWAN technology for radio communications are explored in this study. WPT experiments were performed using continuous wave signal generator followed by amplifier at the transmitter side and RF-DC converters with different parameters at the receiver side. Two pairs of antennas with different gain and directivity were used. According to the experimental results it is possible to accumulate sufficient electrical energy to perform data transmissions at regular time intervals of several seconds. However, the energy requirements of sensor node depend strongly on operation mode of LoRa communication module together with supplementary circuit. Therefore, careful configuration of sensor nodes is required to achieve acceptable performance of wireless sensor network (WSN). Because of specific propagation of electromagnetic radiation in indoor environment there are locations with minimum available power even close to the transmitter. Consequently, installation of sensor nodes in closed areas requires knowledge of electromagnetic field distribution around transmitter.