Analyzing the near and far field using finite element method

In this paper, the railgun is assumed to be an antenna and simulated with finite element method. The caliber of railgun is 10 mm × 10 mm, rail thickness is 10mm and rail length is 400mm. Normally, one assumes that the railgun is operated in the far-field and the near-field region, and radiation patterns are computed in the far-field region where the transmitted wave of the transmitting antenna resembles a spherical wave from a point source that only locally resembles a uniform plane wave. At first, the H-field on the cross section of the rails is computed and shown in figure. Next, power radiation and the maximum value of the E-field in the near and far field are obtained as a function of frequency and shown in the some figures. Polar radiation patterns for versus frequency (1 kHz to 1 MHz) in the near and far field region are calculated as a function of angle and given in the some polar figures. Finally, three dimensional radiation patterns for both regions are shown in the some figures.