Analysis of Some Techniques Used in Modern LF-VLF Radiation Systems

A technique for radiating relatively broad-band pulses from narrow-band antennas is presented and analyzed. Good efficiency and bandwidth are obtained through the techniques of 1) forcing the antenna current to rise to the required level within the required time, and 2) feedback of stored energy from the high-Q antenna to the power supply during the pulse decay. A sample computation is made on a Loran-type pulse having a peak radiated power of 3 kW from a 3O0-foot umbrella antenna. This system has an antenna broad-banding transmitter efficiency product of over three times that of a system using the brute force technique of resistance loading.