Optimization of antenna systems of communication lines is considered. The book contains three sections. The first section is devoted to clarifying the role of antenna systems in radio communication lines (line of sight and tropospheric), taking into account multipath and system requirements. The issues of communication stability were considered and the role of the antenna system as a factor that largely determines this stability was determined, as well as the issues of minimizing thermal and transient noise on lines using purely antenna methods. The second section of the book is devoted to optimization of directional properties of passive relays of scattering, reflecting and refracting types. The third section discusses some particular issues of optimizing mirror antennas, namely, reducing aperture lateral radiation while maintaining high efficiency, optimizing support structures, creating special-shaped radiation patterns to ensure increased stability, etc.