## 5 Conclusions  
With the establishment of a closed-loop electromagnetic compatibility radiation testing method, we can utilize simulation software to optimize S-parameters, significantly improving the stability and performance of communication systems. This optimization not only aids in effectively reducing costs, but also ensures the repeatability and comparability of measurement results, laying a solid foundation for subsequent research and applications. Furthermore, this method allows for a more comprehensive and accurate assessment of the electromagnetic compatibility of connected vehicle communication antennas, enhancing their performance in complex environments, thereby further ensuring the safety and effectiveness of connected vehicles' communications. This research method has already assisted a company in determining the optimal placement of antennas on vehicles in actual engineering applications. The introduction of simulation testing enables us to accurately and reproducibly replicate the antenna propagation paths of real-world scenarios within an anechoic chamber, offering the advantage of providing consistent and comparable measurement results. However, establishing a simulation testing environment for measurements also presents certain limitations. First, the range of actual scenarios that simulation testing can represent is limited; it is primarily suitable for modeling classic environments and struggles to encompass all complex real-world conditions. Second, simulation testing typically does not account for the impact of external noise signals, which may lead to discrepancies between the results and the actual environment. Lastly, conducting measurements of the throughput between the transmitting and receiving antennas in practical experiments and comparing these with simulation data and the MCL would yield more comprehensive and refined results. The proposed method in this study offers a simple and efficient approach to enhancing the efficiency and quality of wireless communication systems in connected vehicles. It particularly provides a powerful tool for antenna testing in commercial vehicles, significantly improving testing efficiency, reducing costs, and optimizing designs. However, the accuracy of the simulation results heavily depends on the precision of the models. A key focus for future research will be on developing electromagnetic field and channel models that more closely resemble real-world environments. Additionally, future work will refine practical testing by integrating actual test data and establishing mathematical models based on the relationship between throughput and S-parameters to further optimize the testing framework, thereby enhancing the practicality of the proposed method. It will also be essential to simulate or test other critical or specialized antennas on vehicles to prevent potential incompatibility issues. Based on OTA performance simulation analyses across various fields, including 5G, millimeter-wave communication, the Internet of Things, and vehicular communication [12, 13], combining the proposed method with OTA testing could unlock significant potential in applications such as V2X and 5G. This research not only contributes to the advancement of antenna testing techniques, but also supports the broader goal of enhancing the performance and reliability of connected vehicle communication systems. By improving testing efficiency and accuracy, this method has the potential to accelerate the development of next-generation automotive communication technologies, ultimately facilitating the realization of fully autonomous driving and seamless vehicle connectivity. **Author Contributions:** Conceptualization, W.W. and J.J.; methodology, J.J.; validation, K.S., W.C. and W.W.; investigation, Q.C. ; writing--original draft preparation, W.W.; writing--review and editing, M.Y. ; supervision, M.Y. All authors have read and agreed to the published version of the manuscript.