This book provides a comprehensive analysis of the conventional techniques used for chipless RFID tag encoding and their limitations. After this analysis, the authors discuss new approaches for chipless RFID encoding and detection. The book is divided into two main sections: The first section introduces the fundamentals of electromagnetic (EM) imaging at mm-wave band for data extraction along with the EM imaging synthetic aperture radar (SAR) technique to enhance the content capacity of chipless RFID systems. The second section presents smart tag detection techniques for existing chipless RFID systems and a Multiple-Input and Multiple-Output (MIMO) based tag detection technique to improve the spectral efficiency and increased data bit capacity The book concludes with a discussion of how the MIMO approach can be combined with the image based technique to introduce a complete solution with a fast imaging approach for chipless RFID systems.