Optimal Design Of Rectenna Array For Wireless Power Transmission

With the rise of IOT(Internet of Things)applications,the importance of WPT(Wireless Power Transmission)technology is increasing.As a vital part of wireless energy transmission systems,rectifying antennas assume the key tasks of electromagnetic energy reception and RF-DC.In order to receive sufficient RF energy at a limited power density,in practical scientific research and market applications,rectenna are mostly implemented in the form of arrays by increasing the effective aperture and gain of the antenna.However.The unnecessary loss caused by the polarization direction,radiation direction of the antenna array and the array feed network greatly limits the efficiency of the WPT system.In this paper,rectennas such as full-polarized rectenna,polarization-insensitive rectenna arrays with different power combining methods,and rectenna arrays for receiving RF energy in multiple directions are used to reduce unnecessary power loss during rectenna array operation,improve the transmission efficiency and increase the possibility of receiving RF energy by the rectenna.The main research contents of this article include:Firstly,this letter presents two 2×2 polarization-insensitive dual-polarized rectenna arrays with different power combining strategies for wireless power transmission applications.With a dual-polarized antenna array,the incident wave can be received and decomposed into the horizontally-and vertically-polarized components,which are equally redistributed by a hybrid coupler.By this means,the efficiency of the rectenna,in which the power is equally input to the two rectifiers in parallel,is independent of the incident wave's polarization.Based on the equal power routing mechanism,two rectenna arrays using the RF and DC combining strategies are designed and analyzed.Measurement results show that both rectenna arrays are insensitive to the incident wave's polarization,and have their own advantages and disadvantages.Secondly,this paper presents a rectenna array with an omnidirectional reception and robust efficiency for RF energy harvesting in the internet of things(Io T)applications.Three elements formed by four Yagi antennas and the rectifying circurt make up the final 1×3 rectenna array.And three rectifiers in parallel connected to the output ports of the hybrid coupler composes the rectifying circle.The array works at 2.45 GHz with an omnidirectional radiation pattern.The measured maximum gain is 10.4d Bi with vertical polarization.Simulation and measurement results prove the performance of the designed rectenna array.