Antenna impedance correction for low power energy harvesting devices

In this paper, a two-step methodology is presented to design a low power wireless energy harvesting device. The rectenna system, consisting of an half-wave rectifier circuit and a non-50 ohms antenna, is designed to archive maximal power transfer at some specified frequency and power level. The main idea of this work is to obtain maximum efficiency avoiding complex impedance matching circuits. First, the rectifier circuit is designed and its input impedance is measured under the desired operating conditions (frequency range and input power levels). Then, the antenna geometry is optimized to match the complex impedance of the rectifier. Results are presented for a 2.45 GHz rectenna. The performance of the non-50 ohms antenna is compared to a conventional one.