Abstract:
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The objective of this thesis is to draw, simulate and optimize a remote alimentation device
for a wireless sensor, low power, short range, powered by the energy transported over the
RF signal. This signal working at UHF frequencies, in particular at 863/870 MHz. The
combination of two key components, that is a rectifier circuit based on using Schottky
diodes and a folded dipole antenna at
λ/2, represents the main elements for a possible
remote alimentation system. The connection of the previous elements forms the rectenna
element. This conversion system allows finding a DC voltage, by the energy harvested
from the ambient RF power. This direct voltage is destined to an energy storage block,
presents on each sensor platform. So, it is necessary constantly provide, to the sensor
platform, a voltage flow that is sufficient to keep the device operative, for every working
mode. The aim is to maximize the power-conversion efficiency of the rectenna for inputpower
level. A comparison between the stored energy and consumed energy, is
fundamental in order to achieve a system able to keep the battery charged, for a specific
electric load. It will be employed a method of directly conjugate-matching between the
rectifying circuit and the folded dipole antenna, so that this matching network, between
the two elements, can improve the rectenna efficiency. |