Optimum integration of passive UHF RFID tag-rectenna in a single feed dual band antenna

In this paper, a design approach for the efficient integration of passive RFID tag operating at UHF 868 MHz for RFID communication and a rectifier operating at 2.45 GHz for energy harvesting application, both in a single feed dual band antenna is presented. Initially, the RFID chip and the rectifier element were characterized. Therefore, the step by step design process for the integration of each element is carried over, for a maximum power transfer to the passive RFID chip and the rectifying circuitry. The non-linear effects of rectifier and RFID chip are considered in an electric-electromagnetic co-simulation, ensuring the conditions at the threshold activation power at the RFID chip. 36.9 % RF-to-DC conversion efficiency is ensured at 2.45 GHz for -10 dBm input power. The sufficient isolation is provided at both frequencies to support an RFID communication and at the same time, harvesting from the 2.45 GHz band.