A study on the analysis of rectenna efficiency for wireless power transmission

We designed and manufactured microstrip patch, dipole and Yagi-Uda antennas mainly used in the existing rectenna (rectifying antenna) and then analyzed the RF-DC conversion efficiency of wireless power transmission system. From the result of measuring RF-DC conversion efficiency with loads of each rectenna element designed and manufactured in this study, we found that the maximum efficiency would be 75.6% at 400 /spl Omega/ of load resistance in patch type, 69.75% at 360 /spl Omega/ in dipole type, and 81.3% at 270 /spl Omega/ in Yagi-Uda type. Under these optimum load conditions, the maximum conversion efficiency in the RF-DC conversion efficiency experiment was determined within /spl plusmn/20% in case of the existing patch and dipole rectennas but for Yagi-Uda, it was determined within /spl plusmn/13%.