This accessible and comprehensive book provides an introduction to the basic concepts and key circuits of radio frequency systems, covering fundamental principles that apply to all radio devices, from wireless data transceivers on semiconductor chips to high-power broadcast transmitters. Topics covered include filters, amplifiers, oscillators, modulators, low-noise amplifiers, phase-locked loops, and transformers. The author describes applications of radio frequency systems in such areas as communications, radio and television broadcasting, radar, and radio astronomy. The book contains many exercises, and assumes only a knowledge of elementary electronics and circuit analysis. It will be an ideal textbook for junior and senior courses in electrical engineering, as well as an invaluable reference for researchers and professional engineers in this area, or for those moving into the field of wireless communications.