Introduction: the analysis of the well-known literature shows that the use of various types of four-pole devices (reactive, resistive, complex) allows to increase the area of physical feasibility of the stationary generation mode. The purpose of the work: increasing the area of physical feasibility of the stationary mode of generation by optimizing the parameters of the matching mixed four-poles. One part of such four-pole devices consists only of resistive elements, and the second part consists only of reactive elements. Materials and methods: four-pole theory, matrix algebra, decomposition method, method of synthesis of microwave control devices, immitance stability criterion. Results: mathematical models of matching mixed four-pole devices are obtained in the form of relationships between the elements of their transmission matrix and the dependencies of the resistances of their two-pole devices on the frequency, optimal according to the criterion of ensuring a stationary generation mode. Conclusion: a comparative analysis of the theoretical results (frequency response and frequency response of the autogenerator in the amplification mode) obtained by mathematical modeling in the MathCad system, and the experimental results obtained by circuit modeling in the OrCad (in the amplification mode) and MicroCap (in the generation mode) systems shows their satisfactory coincidence. The frequency response and frequency response in the amplification mode are similar to the amplitude and phase spectra of the generated oscillations in the generation mode.