A transmission-line type of EMP simulator, consisting of two conductors with a central parallel plate region has been designed, fabricated and tested. It has been named SEMIRAMIS-I, which stands for Simulateur Electromagnetique a Impulsion Raide pour des Mesures Industrielles et Scientifiques. This simulator can be energized by either a CW or a transient pulse source. Testing was performed with ELGAL's EM-103 pulser (20 kV-100 kV, 7-9 ns risetime, 150 ns FWHM). The desired working volume is about 3 m long×1 m wide×1 m high. The initial design has been experimentally optimized. Measurements have been made of the simulated electromagnetic environment