Design of a Wide Input Power Dual-Frequency Rectifying Antenna

A Hilbert dual-frequency rectifying antenna is proposed to harvest RF energy in space environment, which can recover wireless energy effectively. The rectifier circuit consists of impedance matching network, Cockcroft-walton voltage doubling rectifier circuit and DC-pass filter. The receiving antenna adopts the symmetrical dipole antenna mode, and the main body is composed of Hilbert fractal structure and helical structure to ensure the omnidirectional antenna radiation. Antenna operating center frequencies are 0.94GHz and 2.45GHz. The impedance matching network is designed based on $\lambda$/4 dual-frequency coupler, which can reduce RF signal reflection and improve energy utilization efficiency. The rectifier circuit uses HMSS-2852 Schottky diodes with low starting conditions and suitable for ambient RF energy with low energy density. The rectifier topology adopts Cockcroft-walton voltage doubling rectifier circuit which has the highest rectifier efficiency at the operating frequency. DC-pass filter adopts fan stub structure to suppress fundamental wave and high order harmonics and improve the efficiency of RF energy rectification. ADS simulation results show that the maximum rectifying efficiency of the rectifying antenna at 0.94GHz and 2.4GHz are 70.84% and 56.77%, respectively. At the 0.94GHz and 2.4GHz frequencies, In the wide input power range of -4.4dBm $\sim$ 17.4dBm and 2.4dBm $\sim$ 16.8dBm, the rectification efficiency is greater than 40%. The rectifier circuit has the characteristics of dual-frequency and wide input power, which can be applied to power to low-power devices such as wireless sensors.