Efficiency enhancement using beam forming array antenna for microwave-based wireless energy transfer

Microwave-based wireless power transfer can be used for low power consumption applications such as wireless sensor network because this technology can cover long distance. There are some methods to improve transmission efficiency. First, the antenna gain can be improved by using a directional antenna. And second, the conversion loss of microwave to DC can be decreased by optimizing the diode and impedance matching circuit [1]. In this paper, directional antenna hiring beam forming is proposed. For the beam forming, a two by two array patch antenna is designed. The proposed structure has about 11 times higher gain than single patch antenna in any condition. The impedance matching circuit is optimized at 2.4GHz~2.45GHz, because the loss of 2.4GHz frequency band is lower than other frequency band.