Designing antennas in the presence of electrically large and complex structures such as cars or aircrafts has become an important issue for next generation communication systems. Based on the principle of equivalence, the hybridization approach integrating FIT-UTD techniques has shown its superiority in terms of its computing efficiency. In such approach, discrete samplings of continuous electric or magnetic field components resulted from low frequency (LF) sub-domain are required to be converted to the excitation current sources for the high frequency (HF) sub-domain. Thus, the overall accuracy of the calculation results will strongly depend on the similarities between the sampled and original field distributions with both the magnitude and phase involved. In this paper, convergence study of electric and magnetic current sampling is performed. Impact of the different sampling profiles on the overall accuracy is also investigated through numerical examples. Results reveal that convergence of the far-field radiation patterns are closely related to the sampling profiles.