Contribuições ao projeto de leitores e dispositivos sensores baseados em retroespalhamento sem chip, de baixo custo.
Chipless tags for objects identification have been proposed as a low-cost alternative to the well-known chipped Radio Frequency IDentification (RFID) tags technology. More recently, chipless sensors havealso been indicated for specific applications in which RFID-based sensor are not very suitable, such as in harsh environments or ultra-low cost item monitoring. This research have focused on the study of a chipless monitoring system. It was identified that the reading range is one of the most important concerns of these systems, specifically when both the sensor and the reader are size restricted due to a specific application. Consequently, in this work, a new sensor design is proposed to tackle this issue. Several prototypes of the sensor have been implemented in low-cost substrates, such as common PCB glass epoxy-based laminates, and flexible substrates such as plastic and paper. These have shown comparable results to the reported sensors in literature in terms of sensitivity and, more importantly, a superior radar cross section level considering its reduced size. In addition to the sensor, a theoretical analysis and some tests were conducted to prove the need of implementing self-interference cancellation techniques in single-antenna monostatic chipless readers for improving the readability of the tag. Both proposals, on the sensor and on the reader side, can contribute to the reading range enhancement in frequency coded chipless systems.