Additively Manufactured Compact UHF RFID Tag Employing Slow-Wave Structures

Smart connected things that can sense, interact, and share data have a huge potential in enabling a smart environment. Due to the rising interest in realizing the internet of things to provide smart services in smart cities, there is a requirement of vast deployment; therefore, things/tags need to be low in cost and compact in size. Radio Frequency Identification (RFID) is one of the technologies that can enable sensing and wireless communication between things. In this paper, additive manufacturing is used to minimize the cost of RFID tags while slow-wave structures (SWS) are explored to make them compact. The largest element of RFID tags i.e. antenna is initially taken as a standard half-wave dipole then folded to employ SWS along the parallel conductors. The process of folding and SWS loading have been carefully performed to ensure decent radiation efficiency and read range. To fabricate the proposed RFID tag, silver nanowires-based conductive ink is employed while the substrate is 3D printed. The overall tag size is 54 x 56 x 0.5 mm
³
(ka=0.71), and it has a read range of 6.4 m at 867 MHz.