This textbook covers a typical modern syllabus in radio frequency or microwave design at final year undergraduate or first year postgraduate level. The content has been chosen to include all of the basic topics necessary to give a rigorous introduction to high-frequency technology. Both the content and presentation reflect the considerable experience which both authors have in teaching and research at university level. The material is presented from first principles, and relies only on students having a reasonable grasp of basic electronic principles. One of the key features of the book is the inclusion of an extensive set of worked examples to guide the student reader who has no prior knowledge of the subject.