Power amplifier design challenges in UHF and VHF transmitters

UHF (225 MHz-400 MHz) and VHF (118 MHz-144 MHz) transmitters in aeronautical domain are among the most strict telecommunication equipments. ICAO (International Civil Aviation Organization) forcasts 4% traffic growth over the coming 15 years. Due to this evolution, the data exchange between the planes and the infrastructure increases more and more resulting in a saturation of the frequency bands allocated to this service. The main purpose of this paper is to describe Power Amplifier (PA) conception challenges. Distant noise (to carrier) issue is resolved by the right PA´s structure choice. Reliable and well-chosen linearization method is necessary in close noise (to carrier) significant reduction.