Study on the Solution Method of Correlation Coefficient in Stochastic FDTD Transient Field Calculation Based on Taylor Expansion

The Stochastic Finite-Difference Time-Domain (SFDTD) method based on Taylor expansion is an effective numerical method for quantifying uncertain parameters in electromagnetic models, but its accuracy is limited by the prediction of correlation coefficients between the electrical properties and fields. In the application of electromagnetic models, the Monte Carlo Correlation Coefficient (MC-CC) method for estimating the correlation coefficient requires approximately 1% of the running times of the Monte Carlo method. Meanwhile, when the S-FDTD method is used for transient field simulation, the MC-CC method has difficulty in estimating the correlation coefficients of the S-FDTD method. In this letter, based on the Non-Intrusive Polynomial Chaos (NIPC) method, the correlation coefficients in the S-FDTD method are estimated, enabling the S-FDTD method to be applied to high-precision simulation of the random properties of transient fields. Two different random ionosphere models were used to simulate the propagation process of electromagnetic waves and obtain the correlation coefficients of the S-FDTD method. The effectiveness of the proposed method was verified by comparing it with the Monte Carlo and MC-CC methods.