An Accurate Interpolation Scheme With Derivative Term for Generating MoM Matrices in Frequency Sweeps

A new accurate impedance matrix interpolation algorithm is proposed for frequency sweeps arising in the method of moments (MoM). Its performance is optimized by specifying the choice of the internal frequency sample within a given frequency band. The modified matrix element employed in this scheme is a product of the normalized frequency and the remaining part of the impedance matrix element after factoring out the dominant phase term, where the normalized frequency means that the frequency is normalized by the highest frequency. Based on the modified matrices at three normalized frequency samples and the derivative of the modified matrix at the internal sample, the matrices over the frequency band are fast generated via interpolation. The proposed scheme requires the same storage as the Hermite scheme and 25% storage more than the improved Lagrange scheme. Numerical examples indicate that it yields more accurate matrices over the frequency band than both the Hermite scheme and the improved Lagrange scheme.