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This paper presents a novel antenna element with varying complex input impedances from 203 to 303 Ω for the real part and 360 to 127 Ω for the imaginary part and a wide circular polarized (CP) beam that could be used for high efficiency rectenna applications. The efficiency of the antenna is about 88%. Tuning the real and imaginary parts of the antenna impedances to the desired values directly matches the complex conjugate to the rectifier impedance. The antenna element is designed with an artificial magnetic conductor at the back of a spiral antenna operating at a center frequency of 2.5 GHz with a CP beam width of 179° and a bandwidth of 400 MHz. This prototype antenna overcomes the low polarization losses and the need for a matching network, which is useful for high efficiency rectenna applications.