A Compact Dual-Frequency Rectifying Antenna With High-Orders Harmonic-Rejection

This paper proposes a novel dual-frequency rectifying antenna operating at 2.45 and 5.8 GHz. The rectifying antenna consists of two compact ring slot antennas, a hairpin lowpass filter, and a rectifying circuit. The annual slot ring antenna uses a meander line structure to reduce its size to 52% of the regular ring slot antenna. The hairpin filter helps suppress the second order and the third order harmonics of both operation frequencies. The dual-frequency rectifying antenna (rectenna) achieves RF-to-dc conversion efficiencies of 65% and 46% at 2.45 and 5.8 GHz, respectively, while the power density is 10 mW/cm². The rectenna is the smallest dual-frequency rectenna ever reported.