This paper presents the evaluation, by COMSOL software simulations, of the magnetic fields due to a circular coil [1-3] when a 0.7 mm metallic plate is placed near the coil. We have analysed the variation of this magnetic field Be as function of the frequency as well of z (perpendicular to the circular coil). We show that a clear evanescent magnetic field B e , near the metallic plate, appears due to the skin effect related to the "Plasmon current". We analyse also the particular effect near the metallic plate concerning the increasing value of frequencyThe comparison of the results shows that the developed model and the performed experimental measurements are accurate and effective.