Starting from the uniform disk current model, an analytical solution for the electromagnetic pulse axial energy radiation is derived and a physical meaning then given to the axial energy propagation characteristics of a unit antenna. From this solution, a point-source approximation model in the time domain is introduced. Parameters such as the energy propagation characteristics and beamwidth of the electromagnetic pulse beam radiating from arrayed antenna are analyzed theoretically. An arrayed transient electromagnetic pulse generator is developed incorporating a 23×16 ultra-wideband tapered slot antenna integrated with a Blumlein formation line and photoconductive semiconductor switch. Experiments performed over a 2.5 km range confirm that the arrayed transient electromagnetic pulse can propagate in free space with the specified waveform. Moreover, the field components can be superposed in phase, and the radiation beam can be focused into a single pulse. Results from calculations are in agreement with experimental results within the measurement uncertainties.
A GaAs Photoconductive Semiconductor Switch (PCSS) with a 3-mm gap between the two opposed contact electrodes was developed with carefully chosen GaAs material, mechanical structure design, contact fabrication techniques and its insulation protection. It is charged by a pulse power supply under a bias of 15 kV, illuminated by laser pulses of 1064 nm in wavelength, 56.12 μJ in optical energy per shot and 1 kHz pulse repetition rate (PRR). The GaAs PCSS can last for more than 3.6×106 shots and produce output pulses of 2 MW in peak power, 2 ns pulse duration and 65 ps time jitter from a 50-Ω load of the oscilloscope. When an electric field of 100 kV/cm bias was applied, the peak power of the load was measured at 10 MW. A series of measurements on the voltage conversion rates (VCR) and time jitters have been carried out as the bias voltage increases. In particular, taking into account the dependence of optical absorption coefficient on the bias voltages, the curve of the VCR changes with the bias voltages were analyzed quantitatively.
YANG HongChun CUI HaiJuan SUN YunQing ZENG Gang WU MingHe
