The book Radiocommunications. Theory and Principles is a compilation of the class notes and the knowledge acquired by the authors throughout their academic experience. This document compiles the extensive subject matter of the radio communication systems and synthesizes a proposal to be implemented in a semester within an Electronic Engineering program. This text is a complement to the many literary works that exist on the topic. The book is adapted to the current national context, and its content ranges from the introduction to radiocommunication systems to the estimation of the wireless channel. The various topics discussed (radio systems, noise, propagation, radiation, and antennas) are accompanied by examples and contextualized exercises.