A highly efficient rectenna applicable in medical sensors and low power terminals is proposed in the paper. The rectenna operates at ISM (Industrial Scientific Medical) band of 2.45 GHz and employs integrated antenna and Villard voltage doubler circuit to obtain high conversion efficiency. Fractal structure is applied on the antenna for size reduction. The simulated output showed conversion efficiency of 30% and 64% respectively for basic rectifier circuit and Villard voltage doubler circuit having respective load resistance of 200 Ω and 400 Ω. So, Villard voltage doubler circuit is chosen as rectifier circuit for fabrication in rectenna design. The fabricated rectenna has conversion efficiency of 45% for input power of 15 ㏈m and load resistance of 400 Ω. The measured result of antenna displays reflection loss of -22.69㏈, maximum gain of 3.26 ㏈i and impedance characteristic is matched to 46 Ω. Hence, rectenna consisting of miniaturized fractal antenna and Villard voltage doubler circuit is presented to obtain high RF to DC conversion efficiency.