The necessity of using fiber-optic communication lines (FOCL) for transmitting microwave signals in radar complexes is substantiated. The advantages of the use of FOCL when working with microwave signals and testing various antennas are noted. A system with a fiber optic system has been developed to measure the parameters of an active phased array antenna (APAA) in the far zone. The choice of the components of the system is justified and their characteristics are measured. The results of research on the operation of the developed system are presented.