Measurement of transmit system bandwidths on very high power low frequency transmit antenna systems

Low frequency radio systems are used for a variety of applications in navigation and submarine communications. These systems typically include high power transmitters (50-1000 KW) that drive large but very narrowband antennas. There are a number of systems in operation throughout the world, and each one is unique in transmitter type, antenna size, tuning components, and bandwidth. Signals transmitted by these systems are normally continuous wave (CW) in navigation systems and frequency shift keying in communication systems. For communications applications, knowledge of overall system bandwidth is very important in achieving reasonable data rates while minimizing intersymbol distortion due to narrowband effects. Because of the very high power of the transmitters and the complexity of the tuning systems and antennas, making accurate measurements of full power system bandwidth has been difficult. This paper looks at techniques used to measure overall system bandwidth and presents data from a typical site.<>