中文摘要：

为了研究多桨型船舶在浅海中运动时所产生的轴频电磁场传播特性，基于单个时谐垂直电偶极子建模方法，推导得出了多个时谐垂直电偶极子的电磁场解析表达式。通过建立单个时谐垂直电偶极子在三层介质中匀速运动时的物理模型，从相位和频率两方面，按照矢量叠加原理求解 n 个时谐垂直电偶极子在固定场点产生的电磁场，为多桨型船舶的轴频电磁场在浅海中的传播特性提供了理论依据。通过数值仿真计算得出：在频率相同、相位均为0时所产生的电磁场最大，相位相同时频率对轴频电磁场的影响并不明显。最后通过实验测得的轴频电磁场数据，与理论分析的结果基本吻合，验证了表达式的实用价值。

英文摘要：

For the purpose of studying the transmission characteristics of a shaft-rated（SR）electromagnetic field （EMF）generated by multi-paddle vessels in the neritic sea,the analytical expression was deduced by the multiple time-harmonic vertical electric dipoles model based on the single time-harmonic vertical electric dipole method. Firstly a single time-harmonic vertical electric dipole physical model in the three mediums with uniform motion was estab-lished. From two aspects of phase and frequency,according to the vector superposition principle to solve the n -time harmonic vertical electric dipole in the fixed point,provides the theoretical basis for the propagation characteristics of electromagnetic field multi-impeller shaft frequency of ship in shallow water.All of this provides a theoretical basis for the research of transmission characteristics. Through numerical simulation by use of the Matlab software,conclusions are obtained that at the same frequency the maximum EMF value is generated when all phases are zero,and the effects of the frequency on SR EMF are not obvious. Finally,the experimental results of SR EMF are consistent with the theoretical analysis,verifying the practical value of the expression.