In the teaching of electromagnetic wave radiation in university physics, the focus is on explaining the characteristics of the electromagnetic field in the near and far zone of radiation. Students realize that in the case of electric dipole radiation, the electric field is a longitudinal wave similar to a static field near the radiation source, while in the region far from the radiation source, the electromagnetic wave is a transverse wave. How does the electric field transition from a longitudinal wave to a transverse wave? This transition zone is quite complex and is generally not explained in detail in textbooks. However, this is a question that students are very concerned about. Therefore, this article provides a detailed analysis of electric dipole, magnetic dipole, and electric quadrupole radiation, and calculates in detail the change in the ratio of the longitudinal component to the transverse component of the electric field during the process of electric dipole radiation from the near zone to the far zone, clearly showing the transition process from the near field to the far field.