On Preconditioners of the FFT-JVIE for Inhomogeneous Dielectric Objects

An improved block-diagonal preconditioner (IBDP) is developed for the fast Fourier transform (FFT) accelerated the volume integral equation formulation based on equivalent volumetric currents (FFT-JVIE). A comparative study on the realistic models is carried out among the IBDP, block-diagonal preconditioner (BDP), the previously developed analytical preconditioner (AnP), and the circulant-based preconditioners (CBPs).