Compact circularly polarized multi-band antenna for RFID applications

Abstract

This thesis studies and reports designs of multi-band circularly polarized antennas for Radio Frequency Identification (RFID) applications. RFID is the use of a wireless system for the purposes of automatic identification and tracking, providing a step closer to the reality of connecting the world seamlessly. It follows different standards and could operate in several bands, depending on the country and the application. Multi-band antennas are thus required for the robust operation of RFIDs meeting different specifications. On the other hand, the use of circularly polarized antennas ensures the RFIDs remain capable of receiving-transmitting the signal despite the issues stemming from signal reflections and antenna misalignment. Combining multi-band with circular polarization is a key to the reliable and ubiquitous operation of RFIDs. The thesis is divided into five chapters. Chapter 1 provides a brief overview of the Automatic Identification and Data Capture (AIDC) system and its categories, clarifying the idea behind the introduction to the Radio Frequency Identification technology. Chapter 2 presents the Radio Frequency Identification technology, its history, systems, applications, types and standards. Chapter 3 presents some of the work done on RFID antennas distinguished between the frequency of operation, single and multi-band operations. Furthermore, a brief overview of the antenna polarization will be presented before going into the advantages of circular polarization and how it could be achieved using several designs of single and dual-band circularly polarized antennas for several applications including RFIDs. Chapter 4 presents the design and simulations part, where our studies and reports achieved on several designs of multi-band circularly polarized antennas for RFID applications will be presented. It starts with a study on how to use a slot in order to achieve dual-band operation. After that, several studies on how to get dual-band circularly polarized antennas for RFIDs will be illustrated wher