“…For this reason, the theoretical foundations have already been presented many times. A synthetic description of the theoretical basis related to this article is included in [ 16 ], where an analysis was conducted of the possibility of assessing active stresses in steel elements by measuring electromagnetic diagnostic signals. Many articles were referred to in [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ], where information can be found on the theoretical basis of the applied electromagnetic methods.…”