In this paper, a broadband rectenna for radio frequency (RF) energy harvesting is presented. The proposed rectenna consists of a broadband fractal slot antenna and a voltage doubler rectifier circuit with a novel matching network. First of all, a broadband fractal antenna is proposed, which covers the most frequently encountered frequency bands which are located around 1800 MHz, 2.1 GHz, 2.4 GHz, and 2.45 GHz corresponding to the standards like GSM, UMTS, ISM, and WLAN, respectively. The return loss of the proposed antenna is below -10 dB over the desired frequency bands of the interests. Secondly, a novel dual-band impedance matching technique is employed to a voltage doubler rectifier circuit in order to enhance RF-to-DC conversion efficiency which reaches 45% and up to 72.2% when the input power to the rectifier is -10 dBm and 4 dBm, respectively. Finally, it has been demonstrated that the proposed rectenna is able to harvest RF energy from both GSM-1800 and wireless LAN/Wi-Fi bands. It could be utilized to powerup low-power sensor platforms.