A Review of Chipless RFID Measurement Methods, Response Detection Approaches, and Decoding Techniques

Chipless RFID systems can be considered as a special case of passive RFID systems, where the tag contains no power source and no electronics. Instead, the tag’s information is stored in its structure and accessed through its electromagnetic (EM) scattering response. However, robust response detection, which is primarily a function of the measurement method, measurement equipment, and processing method used, is still a major challenge in the chipless RFID field. The consequences of not properly capturing a tag response include, incorrectly assigning an ID or incorrectly reporting a sensing parameter. Due to the criticality of these challenges, this review seeks to provide an overview of the current measurement methods, equipment architectures, and processing methods as they relate to chipless RFID tag response detection and decoding. Since chipless RFID started gaining popularity around 2005, the developments in this area have been focused on three major categories: time-domain, frequency-domain, and spatial-domain systems. Frequency-domain systems have emerged as the most popular among these three categories, and thus, this review focuses on techniques used for these systems.