The book systematizes numerical methods for modelling and synthesizing radio engineering and telecommunication systems in the microwave range of rectangular and circular waveguides. The author gives the theoretical foundations for the analysis and optimal synthesis of these systems and presents the results of new research. The book uses the HFSS complex to analyse, optimize, and synthesize microwave systems operating on E-type and H-type waves while providing the outcomes. As a result of analysis and synthesis, various microwave devices with improved technical and operational parameters have been developed, and on their basis a new system of waveguide paths is proposed that connects the transmitter and antenna in TV towers. The book is intended for engineers and scientists involved in the design of radio engineering and telecommunication systems.