Abstract: The application of the transfer function relation,Z = AH + BI),to induction study is briefly reviewed. Three dimensional (3D) models are used to calculate the induction vectors and transfer functions for investigating the properties of these quantities and particularly the property of their imaginary components. For square or rectangular conductive bodies with top surface parallel to the ground,the results show two dimensional (2D) behaviour. For a model consisting of two rectangular conductors buried at different depths,the calculated results show that the induction functions are more complex than 2D ones,the coefficients A and B can have similar magnitudes even in the direction of the major axes,and accordingly,the real and imaginary components may point in very different directions.