In this paper, a fast numerical method called the sparse-matrix/canonical-g
rid (SM/CG) method is employed to analyze densely packed microstrip interco
nnects that involve a large number of unknowns. The mixed-potential integra
l equation is solved by using the method of moments in the spatial domain,
The closed-form expressions of the spatial Green's functions of microstrip
structures are obtained from the combination of the fast Hankel transform a
nd the matrix pencil method, The Rao-Wilton-Glisson triangular basis functi
ons are used to convert the integral equation into a matrix equation. The m
atrix equation is then solved by using the SM/CG method, in which the far-i
nteraction portion of the matrix-vector multiplication in the iterative sol
ution is performed by the fast Fourier transforms (FFTs), This is achieved
by the Taylor series expansions of the spatial Green's functions about the
uniformly spaced canonical grid points overlaying the triangular discretiza
tion, Numerical examples are presented to illustrate the accuracy and effic
iency of the proposed method. The SM/CG method has computational complexity
of O(N logN), Furthermore, being FFT-based facilitates the implementation
for parallel computation.