| dc.description.abstract | RF energy transmitting is an approach to deliver charging energy wirelessly, while RF energy harvesting is an approach to re-charge battery by capturing ambient RF energy. A multiband system composed of mutual coupling compensated linear antenna arrays and output LC matched RF-DC rectifier is proposed for RF energy harvesting and transmitting. The designed system operates in standard communication bands such as GSM850, GSM900, GSM1800, GSM1900, WiFi, Bluetooth, and LTE since ample RF ambient signals are present and numerous IoT sensors operates in these frequency bands.
The design starts from a highly efficient double-ring monopole antenna. The proposed antenna has both wideband and multiband features to cover the target operating frequencies. According to Friis transmission equation, the captured/radiated RF power is proportional to the antenna gain, thus antenna array composed of double-ring monopoles is investigated to increase antenna gain. In the proposed four-element antenna array, a four-way RF energy combiner with optimum power combining efficiency is implemented to connect four antennas. Triple-band radiation patterns are synthesized by by mutual coupling compensation structure. The proposed output LC matched RF-DC rectifier is connected to antenna array to convert RF power to DC energy. The rectifier sensitivity and power conversion efficiency is boosted with dual frequency tones.
System measurement results state that not only the antenna gain but also the radiation pattern of antenna array affects the total captured RF power. Antenna array is preferable to be installed at the transmitting side for RF energy transfer, while the single antenna is preferable to be installed at the receiving side for RF energy harvesting. If the receiving area is not limited, then the rectenna array composed of antenna arrays and RF-DC rectifiers can be applied for RF energy harvesting. | en |
