Design and development of High Power Ultra Wideband Systems

High power ultra wideband (UWB) systems can be used for various applications like buried target detection, electrical characterization of materials, space debris detection and as a source for vulnerability studies on electronic circuits. Two high power UWB radiator systems have been developed at APPD, BARC Mumbai. The first one is a 120 kV, 66 Ohm system which uses balanced Transverse Electromagnetic (TEM) horn antenna for radiation of UWB pulse into the atmosphere. Pulse power system for this radiator consists of a Marx Generator and a pulse forming line which can generate a 110 kV, 5 ns pulse with a rise time of ~ 300 picoseconds. A balanced TEM horn type antenna was used in this system. Impedance of this antenna is matched to 66 Ohms at feed end and then gradually varies to match with free space impedance. This antenna can effectively radiate this kind of ultra-short sub-nanosecond rise time pulse. This system has generated an electric field of 10 kV/m at 10 m distance from the source. Second system is a Half Impulse Radiating Antenna (HIRA) based UWB system. HIRA based UWB system consists of three components, MARX generator, pulse forming line and HIRA antenna. MARX can generate maximum of 1000kV voltage pulse to charge the pulse forming line. Voltage pulse generated via discharge of pulse forming line sparkgap is radiated by HIRA. This system has generated an electric field of 20 kV/m at 10 m distance from the source. This article discusses the overall system performance with an emphasis on antenna design details and results.