Book excerpt: The ability of wireless communication devices to transmit reliable information is fundamentally limited by sources of noise related to the electronic components in use. Noise in Radio-Frequency Electronics and its Measurement has five chapters that address the theoretical aspects of this subject, and concludes with a series of exercises and solutions. The book examines the origin and sources of noise inside electronic radio-frequency circuits, their impact in telecommunications, their modeling and their measurement. Particular attention is dedicated to the origins, establishment and significance of formulas that are used when the noise characteristics of an electronic circuit are modeled or measured. This book instructs the reader in the application of the examined methods and their adaptation to solving problems, as well as how to comfortably use the presented formulas.