Investigations on Passive RFID Tag Antenna for UHF Band Applications

Abstract

The use of automatic identification technologies such as radio frequency identification (RFID) to identify, track, and sense the people, items, or objects have evolved significantly owing to its great advantages. RFID System is a real-time processor that helps in tracking the information stored on a tag and to exchange it with the remote device known as the RFID Reader or Interrogator. The essential benefits offered by these RFID systems are automatic and non-line of sight detection at a distance of several meters, portable database, and flexibility towards unfriendly environments result in reduced manual localization work and hence man-power. These advantages also make RFID to be recognized as a cornerstone of the future Internet of Things (IoT) technology. The overall performance of the Passive RFID System in terms of size, cost, and read range depends on the design of the tag antenna. The Passive RFID tag must have a reasonable antenna size with improved gain and radiation efficiency in addition to conjugate impedance matching. Also, as RFID tags are generally designed to operate in a specific region, this limits their practical utility and restricts intercountry operations. Therefore UHF-RFID systems having multiple bands/broadband operations with long read range are in more demand. As an RFID tag needs to be affixed onto different objects therefore, the tag must operate reliably in a changing environment. Hence in addition to have compact and planar geometry, the designed tag must be robust and platform tolerant. In this thesis, methods to develop passive RFID tags exhibiting high read range performance over a single, multiple, and broadband UHF-RFID operation are investigated. Further, the use of artificial magnetic conductor (AMC) structures has been explored to enhance the radiation efficiency and read range of platform-independent tags. In this present research work, we started with a single-band tag design and then extended it for dual/broadband tag designs.