A compact broadband ambient RF energy harvester operating from 1800 MHz up to 2.5 GHz is proposed in this paper. This work is motivated by the huge amount of free and continuously available RF energy in the surroundings that can be utilized into useable energy. Harvest performance is investigated using two antennas in this work, a circular polarized and an array antenna. Due to low ambient power densities, a multistage rectifier is utilized to improve the output dc voltage of the proposed system. Measurements indicate the system is capable of harvesting up to 1.8 Vdc output from nondedicated ambient RF energy sources in an urban area, which is significant in the absence of other energy sources.
