Chipless RFID tags, owing to their low cost, have opened a new way to the identification systems. Chipless RFID tags operating in the time domain have the advantage of being compatible with large reading distances of the order of a few meters, and also can operate in the ISM frequency bands. However, time domain tags developed until now offer poor coding capacity. This thesis proposes a new method to increase the coding capacity of tags operating in time domain by using C-sections, i.e. the transmission lines are folded so as to have tightly coupled zones that give them a dispersive nature. Another approach based on a multi-layer technique was also introduced, in order to increase the coding capacity considerably. Finally, the proof of concept of a humidity sensor tag based on silicon nanowires is also presented.
