2.4GHz square slot antenna and power management circuit for wireless energy harvesting applications

This paper describes a 2.4GHz square slot antenna and power management circuit for wireless energy harvesting applications. The antenna is designed at 2.4GHz. The antenna element comprises of 4 square slots cut on top and ground plane compared to the conventional designs, which has resulted in improved gain and return loss. A half-bridge rectifier comprising of one low threshold schottky diode has been used to minimize the losses through the device at high frequency. The power management circuit implements a synchronous boost converter consisting of one pair of complementary MOSFETs to reduce loss in power stages and improve efficiency of the overall system. The measured results show that with input power of -20dBm, the output voltage is 412mV. The simulated gain of the antenna is 5.7dBi and with a return loss (S₁₁) less than -16dB at resonant frequency (2.44GHz). In addition, the introduction of slots has caused resonant frequency to become lower at 2.44GHz from 3.2GHz. This results in a compact structure.