This book presents the design requirements of antenna integration for modern commercial devices such as smartphones, dongles, and access points. Practical use-case scenarios of smartphone and the design process of the antenna system for the same are highlighted. The feasibility of scaling up sub-6GHz to mmWave antennas is also discussed in detail followed by a plethora of design examples which could be panel mounted to modern-day commercial smartphones. The unique requirement of gain switchability is introduced with feasible practical antenna designs. High efficiency antennas for 5G base stations is introduced along with a design example on planar all-metallic antenna. Beam switchability requirement for base station is illustrated with a couple of compact antenna system examples. Variety of feeding techniques for mmWave antennas is elaborated in this book. Finally, low-cost antenna designs for future wireless devices are illustrated.