This book provides in-depth exposure to emerging technologies and recent advancements in RF, Microwave, and Millimetre Wave Technologies. The book covers the basic concepts along with the recent advancements in designing and developing antennas and circuits for the latest technologies. The concepts of mode compression, Full Duplex communication, massive MIMO, frequency selective surfaces, reflectarrays, and metasurfaces have been discussed in detail. Various types of antennas, such as electrically small antennas, textile antennas, dielectric resonator antennas, etc., to be used for the latest wireless devices, RFID applications are also thoroughly explored. The concept of machine learning to develop data-driven models for antenna design is also discussed briefly to provide readers with an introduction to the ML algorithms. The readers will be able to understand the theoretical concepts and practical design aspects of various antennas, high-frequency circuits, and device modeling. The target audience includes but is not limited to undergraduates, post-graduates, research scholars, academicians, scientists, and professionals who are interested in getting the latest knowledge in the field of RF, Microwave, and Millimetre Wave Technologies.