These days radio _engineering has become a very importantbranch of science solving a large number of problems associatedwith economic, technological and cultural progress. Everyyear, it finds ever increasing application and the number ofpeople using radio equipment constantly grows. Many ofthese people have only rudimentary or no knowledge of radioengineering, although modern radio equipment is often socomplicated that its effective use is impossible without some·training.The wide sphere of radio application in different branchesof science and technology, as well as its close connexion withart and sport has also created a great number of radio amateursin all countries. Some build radio receivers, tape recorders andTV sets, others design radio controlled models, short andultrashortwave transmitters or equipment for a fascinatinggame called "hunting for a fox", etc.All this increases the interest in radio engineering knowledgeon the part of an ever growing number of people. The studyof radio is, however, made more difficult for the majority ofreaders as it is usually explained with the use of higher mathematics.On the other hand, when higher mathematics is notused, many important problems are often oversimplified andtreated without sufficient explanation and demonstration.Moreover radio engineering is a coherent science in which everythingis interrelated and interdependent; therefore lackof understanding of fundamental phenomena and laws preventsthe reader from fully understanding further problems.It is far from clear what one should understand under thename of "radio engineering,' and its fundamentals since thisbranch has been extended, diversified and become interwovenwith many other branches of science and technology. Under"radio engineering" proper one usually understands the use ofelectromagnetic radiation for the obtaining of informationfrom a distant source. This is effected through the use of atransmitting (radiating) device and a receiving device providedconditions for propagation of radio waves are favourable. Inaccordance with this, the book describes the operating principlesof radio transmitters, radio receivers and radiatingdevices, as well as radio wave propagation. It goes withoutsaying that one book cannot exhaustively deal with all the varieties of existing radio circuits and devices; therefore, weconcentrate our attention only on the most important andrepresentative types.Chapters 7, 8, 9 and 12 were written by N. M. Izyumov;the rest, by D. P. Linde.