Essential Radio Astronomy is the only textbook on the subject specifically designed for a one-semester introductory course for advanced undergraduates or graduate students in astronomy and astrophysics. It starts from first principles in order to fill gaps in students' backgrounds, make teaching easier for professors who are not expert radio astronomers, and provide a useful reference to the essential equations used by practitioners. This unique textbook reflects the fact that students of multiwavelength astronomy typically can afford to spend only one semester studying the observational techniques particular to each wavelength band. Essential Radio Astronomy presents only the most crucial concepts--succinctly and accessibly. It covers the general principles behind radio telescopes, receivers, and digital backends without getting bogged down in engineering details. Emphasizing the physical processes in radio sources, the book's approach is shaped by the view that radio astrophysics owes more to thermodynamics than electromagnetism. Proven in the classroom and generously illustrated throughout, Essential Radio Astronomy is an invaluable resource for students and researchers alike. * The only textbook specifically designed for a one-semester course in radio astronomy* Starts from first principles* Makes teaching easier for astronomy professors who are not expert radio astronomers* Emphasizes the physical processes in radio sources* Covers the principles behind radio telescopes and receivers* Provides the essential equations and fundamental constants used by practitioners* Supplementary website includes lecture notes, problem sets, exams, and links to interactive demonstrations* An online illustration package is available to professors