Supplying basic concepts on electromagnetic wave propagation and radiation, and on asymptotic techniques, employed to study propagation in a complex environment, when obstacles are large concerning wavelength. This book also presents basic models for free-space propagation and propagation over a flat or spherical Earth and some important phenomena involved in wireless propagation in a complex environment are illustrated: multipath, fading and delay spread. It also includes application-oriented portions: available models and tools to predict radio wave propagation in urban areas are presented, and an illustrative example of a ray-tracing solver is provided. The new propagation scenarios arising with 5G telecommunication systems are illustrated, and international and national regulations on exposure of the public to electromagnetic fields are introduced. This resource is great for wireless network engineers, academic and industry researchers, engineers in public administration, and students at the masters level.