A Compact Rectenna for Nondirectional Ambient RF Energy Harvesting

The existing RF energy harvesting systems usually assume the location of RF energy source is determined. However, the locations, numbers and power levels of RF energy sources should not be predictable in the practical applications. Therefore, the performances of these systems are usually unsatisfactory. To solve these issues, a compact rectenna comprising a quasi-isotropic patch antenna and a high-efficiency rectifier is proposed. To verify the effectiveness of proposed rectenna, the corresponding measurement setup has been also implemented. It can be found that the rectenna can harvest not only the energy from the RF source with the unpredictable location, but also the energy from several RF sources simultaneously.