In the aspect of air navigation communication the International Civil Aviation Organization (ICAO) has issued the standard protocols. This paper presents the results the research, design and fabrication of a L-band code transmission communication system. The basic units of the system have been designed into the compact modules which were fabricated on basis of modern technology equipped with engineering ADS software package. Findings of survey on the basic units are relatively good, meeting technical requirements to form a system and apply in reality.