The questions of studying the amplitude and phase characteristics of communication channels of radio engineering systems are considered. As part of the research, a homodyne method for converting microwave signals is proposed, which makes it possible to measure amplitude and phase fluctuations with high accuracy and with the utmost simplicity of measuring equipment. The development of the homodyne method of signal transformation for the purposes and tasks of determining the amplitude and phase fluctuations of signals during the propagation of radio waves on open lines of sight is presented. The features of homodyne signal transformation in the presence of various destabilizing factors are considered. The issues of synchronization of reference generators on different parts of the measuring route are considered. The results of theoretical and experimental studies of amplitude and phase fluctuations on land and sea lines of sight are presented. For students and teachers, as well as anyone interested in radio engineering.