Transforming the way we live, work, and engage with our environment, 5G and beyond technologies will provide much higher bandwidth and connectivity to billions of devices. This brings enormous opportunities but of course the widespread deployment of these technologies faces challenges, including the need for reliable connectivity, a diverse range of bandwidths, dynamic spectrum sharing, channel modelling and wave propagation for ultra-dense wireless networks, as well as price pressures. The choice of an antenna system will also be a critical component of all node end devices and will present several design challenges such as size, purpose, shape and placement. In this edited book, the authors bring new approaches for exploiting challenging propagation channels and the development of efficient, cost-effective, scalable, and reliable antenna systems and solutions, as well as future perspectives.