Fundamentals of radio engineering. In 2 parts - These books are part of the course "Fundamentals of Radio Engineering," which for a number of years was read by V. A. Kotelnikov at the Radio Engineering Department of the Moscow Order of Lenin of the V. M. Molotov Energy Institute. The first part contains an introduction that gives a general brief overview of radio engineering, and an analysis of the processes occurring in the simplest radio engineering circuits and their elements. The second part of the basic radio engineering course is devoted to processes in radio engineering devices containing nonlinear elements.