## 6 Conclusions  
This paper introduces a detailed electromagnetic radiation model of an axial flow fan, incorporating components such as the winding, driving circuit PCB, and shell. Numerical computations are conducted using the time-domain finite integral method with field-circuit coupling to analyze the fan's electromagnetic radiation characteristics. To enhance computational efficiency and reduce resource consumption, the Huygens principle is  
\begin{table}
\begin{tabular}{c c c} \hline \hline \(\mathbf{ADM_{tot}}\) & \(\mathbf{FDM_{tot}}\) & \(\mathbf{GDM_{tot}}\) \\ \hline
0.1199/very good & 0.2343/good & 0.2887/good \\ \hline \hline \end{tabular}
\end{table}
Table 4: FSV evaluation results of the two computational models.  
Figure 20: Comparison of electric field intensity at the monitoring point.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Model Type** & **Computational Object** & **No. of Grid** & **Computation Time** \\ \hline Detailed model & Enclosure with fans & 9,719,864 & 59 h 21 min \\ \hline Equivalent model & Equivalent source & 1,813,965 & 11 h 3 min \\  & Enclosure & 136,864 & 9 min \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison of grid parameters and computation time for two models.  
applied to establish an equivalent radiation source model for the fan. The electromagnetic radiation calculation process involves two numerical computations. The comparison of results obtained from both the detailed electromagnetic radiation model and the equivalent radiation source model is evaluated by the FSV technique, which confirms the accuracy and high efficiency of the equivalent calculation model.  
The accuracy of the equivalent model is validated by experimental measurements of the radiated emissions of the axial flow fan, which demonstrates the feasibility and validity of the equivalent source model established based on the Huygens principle in predicting electromagnetic radiation interference from the fan.  
In practical applications, axial flow fans are commonly installed inside electronic enclosures. Through a comparison of the electric field distributions generated by the detailed model and the equivalent model of the axial flow fan within the enclosure, as well as considering the calculation time, the practicality and efficiency of the equivalent method are showcased. In scenarios where multiple interference sources coexist within the enclosure, the equivalent calculation model demonstrates more computational efficiency advantages.  
In conclusion, the electromagnetic radiation model of fans established by the finite integration method holds significant importance in the analysis and prediction of electromagnetic radiation from electronic equipment. The equivalent field source model based on the Huygens principle not only accurately predicts the electromagnetic radiation emission characteristics of the fan but also enhances computational efficiency. This provides an effective method for electromagnetic compatibility analysis and design.  
Conceptualization, J.Y.; Formal analysis, J.X.; Investigation, W.Z.; Methodology, J.Y., X.Z. and W.Z.; Resources, X.Z.; Supervision, P.D.; Validation, J.Y. and J.X.; Writing, original draft, J.Y.; Writing--review & editing, P.D. and B.N. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China under Grant 52175218.  
Not applicable.  
The data supporting the findings of this study are available from the corresponding author upon reasonable request.  
The authors declare no conflict of interest.