The main goal of this thesis was to study the possibility of storing the energy obtained from the rectification of a low-level alternating current (AC) signal used as the input. This divided the research in two main parts: the rectifying circuit, which obtained a direct current (DC) signal from the AC signal available at the input, and the energy storage circuitry, which manipulated the output of the rectifying circuit to obtain a signal that was suitable to deliver charge to an energy storage component, and at the same time provided a way to retrieve the energy stored in said component.Much of the research done so far has dealt with high input powers, over 10dBm, and a load resistance below 1kΩ, achieving very high conversion efficiencies, up to 80-90%. In this work, however, the research was done with lower input power levels, below 0dBm, and load impedance in the order of tenths of kΩ. The efficiencies obtained under these conditions were much lower, under 10%, but the goal of the research was achieved.The work was focused in two frequency bands, 868MHz and 2.4GHz. Thus, different rectifying circuits were designed and manufactured for both bands in order to obtain the optimal performance for the given conditions. The energy storage circuitry, on the other hand, remained the same for both bands, since its behaviour did not depend on the frequency. Two patch antennas, designed by the supervisor of this thesis and manufactured by the author, were used for the final measurements carried out in an anechoic chamber, and the possibility of storing energy from an electromagnetic wave radiated by a transmitting antenna was demonstrated.This research may be further extended to obtain self-sustainable devices that would harvest energy radiated by nearby equipment operating at those frequencies, eliminating the need of an external power source. Moreover, studies might be carried out to harvest energy from the whole frequency spectrum.
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