The sensitivity of passive UHF RFID transponders (Radio FrequencyIdentification) is the key issue, which determines the maximum read range ofan UHF RFID system. During this work the ability of improving the sensitivityusing solar energy harvesting, especially for low light conditions, is shown.To use the additional energy harvested from the examined silicon and organicsolar cells, the passive RFID system is changed into a semi-active one. Thisneeds no changes on the reader hardware itself, only the used RFIC (RadioFrequency Integrated Circuit) of the transponder has to possess an additionalinput pin for an external supply voltage. The silicon and organic cells areevaluated and compared to each other regarding their low light performance.The different cells are examined in a shielded box, which is protected fromthe environmental lighting. Additionally, a demonstrator is shown, which makesthe measurement of the extended read range with respect to the lightingconditions possible. If the cells are completely darkened, the sensitivitygain is ascertained using high capacity super caps. Due to the measurementsan enhancement in range up to 70 % could be guaranteed even under lowlight conditions.
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