High power UHF transmitters using SSPA for flight termination system in test range: A detailed study

This paper discusses on 1KW CW UHF transmitter systems based on solid state power devices used in flight termination system (FTS) in test range. Transmitters based on three different device technologies are studied. These power devices are silicon based bipolar junction transistor (Si-BJT), silicon based double diffused metal oxide transistor (Si-DMOS) and gallium nitride based high electron mobility transistor (GaN HEMT). It aims to present some of our requirement in terms of transmitter's performance in FTS applications. In such application where operating conditions and requirements are very stringent, wideband semiconductor technology is seen as a potential candidate over conventional device technology. A linear and efficient amplifier system is highly required along with good thermal management, broadband operation, reliability and size & weight. System performance parameters like output power, gain, harmonics and IMD are measured for each transmitter and compared. Gallium nitride being a wide band semiconductor and with its HEMT topology provides superior performance in terms of power density, linearity, efficiency and also more reliable.