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A New Type of TEM Horn Antenna for High-Altitude Electromagnetic Pulse Simulator

A new type of transverse electromagnetic (TEM) horn antenna for high-altitude electromagnetic pulse (HEMP) simulator is designed in terms of the structure of circular helix end and shielded plates circuit. The finite-difference time-domain (FDTD) method is applied to build the antenna model and to calculate waveforms of antenna radiation filed. Results suggest that the new type of antenna can broaden the pulse width and raise the peak field strength value of radiated pulses. Furthermore, the improvement of radiation in lower frequencies reaches a degree of several decibels in amplitude frequency spectrum. Meanwhile, a new index called “waveform similarity” for confirming the similarity of field waveforms with that of standard specification is proposed and calculated for near-field waveforms of different TEM horn antennas. It is shown by the new index that the field waveform radiated by the new type of TEM horn antenna is much closer to standard waveform.