Radio systems are widely used forms of wireless technologies across the world in today's time. They form a core area of electrical engineering with widespread applications. This book discusses the fundamentals as well as modern approaches of radio systems through detailed elaboration of topics such as electromagnetics, circuits, propagation, microwaves, etc. It is an essential guide for students who are looking for an elaborate reference on radio systems engineering. A number of latest researches have been included to keep the readers up-to-date with the global concepts in this area of study.