A Read Range Maximization Approach for UWB Surface Acoustic Wave (SAW) RFID Tags based on Interdigital Transducer (IDT) as a Reflector

摘要

Radio Frequency Identification (RFID) technology using readers and ID tags has been deemed to be a promising candidate compared to bar codes, QR codes and others due to Non Line of Sight (NLOS) operability, bulk readability, and longer read range. Silicon based Integrated Circuit (IC) active and passive RFID tags are quite popular. However, such tags are constrained by several factors such as inability to operate under hazardous conditions, less cost efficient, susceptibility towards electromagnetic interference and poor accuracy in metallic environments. To combat such effects, a special type of passive tag called Surface Acoustic Wave (SAW) RFID tag, which possess a very high potential due to its robustness against the above mentioned effects, has received a lot of attention among the researchers. A very popular approach called Open Circuit/Short Circuit (OC/SC) using a strip reflector design to design unique codes has been in existence and can provide a range of 2.4 m on average. Nevertheless, this range is not sufficient to be considered for a remote interrogation RFID system for many long range RFID applications. This paper uses a different reflector design for Ultra Wide Band (UWB) SAW RFID tags based on Inductive Resonant Loading (IRL) where an inductor is loaded across the reflecting IDT. Simulation results show that there is a 15 dB improvement in reflected power using this design which corresponds to an extended range of up to 9.6 m. Such tags can prove to be very useful in various identification applications leading to a better detection of the tags that are located roughly 10 meters away from the RFID reader.