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Projecte llegit

Títol: Radiofrequency energy harvesting in the ISM 868 MHz band

Estudiants que han llegit aquest projecte:

Director/a: GASULLA FORNER, MANUEL

Departament: EEL

Títol: Radiofrequency energy harvesting in the ISM 868 MHz band

Data inici oferta: 08-11-2021     Data finalització oferta: 08-06-2022


Estudis d'assignació del projecte:
    GR ENG SIS TELECOMUN
Tipus: Coordinat    Títol: Radiofrequency energy harvesting in the ISM 2.4 GHz band
 
Lloc de realització: EETAC
 
Paraules clau:
Radiofrequency energy harvesting in the ISM 868 MHz band
 
Descripció del contingut i pla d'activitats:
Radiofrequency (RF) energy can be harvested in order to power
the nodes of the Internet of Things (IoT) either from the
surrounding environment or from dedicated sources. A
particular example are RFID tags powered from nearby RF
transmitters. Thus, its application is transversal to many
applications of the IoT, e.g. in industrial processes,
agriculture, logistics, transport vehicles (including planes),
etc. A conventional RF harvester is mainly composed a rectenna
and a maximum power point tracker (MPPT). The rectena is
composed by an antenna, a matching network and a rectifier.

This proposal aims to design, simulate, and implement an RF
harvester in the ISM 868 MHz band. The proposal is open to be
discussed with the candidate and partially fitted to his/her
abilities, demands and wishes.
 
Overview (resum en anglès):
This TFG take advantage of the electromagnetic energy in the environment to power autonomous sensors, proposes two circuits for energy harvesting (simple circuit and doubler circuit) which are mainly composed of an antenna, a matching network and a rectifier, allowing to transform electromagnetic signals into almost continuous DC signals. The antenna is modeled as an AC voltage source and a series resistor, the matching network is composed of a capacitor and a coil, as for the rectifier, in the simple circuit, a diode and a capacitor are used, in the doubler circuit, two diodes and two capacitors are used creating a voltage multiplier at the rectifier input.

Previous studies demonstrate the feasibility of the simple collector circuit at low powers, using printed circuit boards with discrete elements in the 868 MHz ISM band, in order to obtain new collector circuits for the desired powers of -10 dBm, -20 dBm and -30 dBm. This TFG focuses on finding new values of efficiencies from the previous studies and on the use of microstrip technology in the matching network in order to improve the efficiency of the circuits. Also, in the doubler circuit, an additional rectifier stage is proposed. With the ADS software, simulations focused on increasing the efficiencies for the matching networks are obtained, using ideal, discrete and microstrip components. Thanks to the use of ideal components in the matching network, it can be validated that the proposed circuits have high efficiency at low powers. Therefore, it is proposed to perform matching networks with discrete elements in order to design RF collector circuits, but it can be seen how the efficiencies decrease. Therefore, new design possibilities are investigated using microstrip technology to increase efficiencies, first of all, the feasibility of microstrip lines in the use of RF collector circuits at low powers is analyzed. Then, the losses obtained by a microstrip element are analyzed and compared with the losses of discrete circuits, thus replacing the matching network consisting of a capacitor and a coil to designs made exclusively with microstrip technology. In order to validate the simulations performed in the ADS software, it is desired to design and print two printed circuit boards to be analyzed in the laboratory of the EETAC (Polytechnic University of Catalonia).

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