A Novel Dual-Frequency Circularly Polarized Rectenna For Wireless Power Transmission

With the rapid development of wireless charging technology,rectennas of multi-frequencies,circular polarization and miniaturization are required.These rectennas can collect more energy,adapt to smaller devices and achieve higher rectifying efficiency under the condition of low input power.In this paper,the performance of rectifier antenna is studied and analyzed comprehensively.And two new dual-frequency circularly polarized rectifier antennas are designed.The main research work and innovations are as follows:(1)By adopting the theory of circular polarization and multi-frequency technology into antenna design,a dual-frequency circularly polarized receiving antenna is designed to collect RF energy in multiple frequency bands.The antenna is designed at resonate frequency of both 2.45 GHz and 5.8 GHz through a cross-shaped slot,and circularly polarized waves are generated by cutting two corners on the diagonal of the patch.(2)A rectification circuit corresponding to the receiving antenna is designed,focusing on the design of a dual-frequency matching network and a DC filter.The design achieves a dual-frequency matching network by double-branch joints.And a smaller-sized DC filter is realized by combining fan-shaped and linear branches.The key parameters were simulated and analyzed using the joint simulation of the schematic and the layout.The rectifier circuit achieves good characteristics at both frequencies,and the rectification efficiency is 75.6%and 71.4%,respectively.(3)A dual-frequency circularly polarized harmonic suppression antenna is proposed to suppress the system harmonics.The antenna achieves the function of harmonic suppression by using defective ground structure.Integrating harmonic suppression into the antenna simplifies the back-end circuit and reduces losses.Through simulation analysis,the return loss of the second harmonic of its working frequency is less than-2dB.(4)The corresponding rectifier circuit is designed according to the performance of the receiving antenna.In order to reduce its mismatch loss,the matching network structure is adjusted.The simulation results show that the rectification efficiency is further improved,which is 78.7%and 73.9%respectively.After the joint simulation of the schematic and the layout,the physical processing test is carried out,and the rectification efficiency is 59.4%and 52.7%,respectively.