Novel Design of 2.45-GHz Rectenna Element and Array for Wireless Power Transmission

A novel design of 2.45-GHz rectifying antenna (rectenna), which is composed of antenna element, two-element series-fed array, and four-element cascaded array, has been proposed in this paper. The array designs are introduced in order to adapt various power density is used in the array, especially in near-field of the transmitting antenna, in this case, the power density in the center and far away from center differs greatly. The compact low-profile air supported microstrip antenna is introduced as receiving antenna element in order to reduce substrate loss. The rectifying circuit has been designed and optimized using ADS software. The diode in the rectifying circuit is installed in series and the capacitance is replaced by microstrip line as dc pass filter. A maximum RF to dc conversion efficiency of the rectifying circuit can reach 80% when the input power is 21 dBm and 3500-Ω resistive load is connected to the circuit end through experiment. The rectenna exhibits a maximum efficiency of 77.2% and an output dc voltage of 18.5 V. The proposed rectenna element and the array can be easily expanded to a large scale integrated rectenna arrays, it will be practically attractive for wireless power transmission system design.