A rectenna for high efficiency RF-to-DC wireless energy harvesting that includes an off-center-fed dipole antenna and a rectifying circuit, wherein the rectifying circuit comprises at least one rectifying diode. The input impedance of the antenna may be directly conjugate matched to the impedance of the rectifying circuit over a wide range of frequencies and/or under different operating conditions. The impedance matching network required by a conventional rectenna system may therefore be eliminated using the methods disclosed for the design and implementation of the rectenna. The rectenna offers consistently high RF-to-DC power conversion efficiency over a wide range of frequencies and under different operating conditions. The rectenna may be connectible to a rectifying circuit utilizing different types of rectifying diodes.