Abstract: The electromagnetic field tensor method is used to calculate the electromagnetic fields inside a parallel-plate simulator and analytical expressions for the field distributions are derived in time domain. The solid metal plates are approximated as wire meshes according to the simulator structures, which are composed of the middle flat plates, the front and back triangular plates. The amplitudes of the electromagnetic field can be determined by the superposition of the different retarded time currents in the wire segments, and the direction can be determined by the simple unit vector operations of the wire segments and field point position. Calculated results show that the fields between the middle flat plates have the transverse electromagnetic distribution properties, and the field compon