Preconditioned adaptive integral method for the analysis of planar microstrip structures

Adaptive integral method based on far-field expansion is introduced to speed up the analysis of the planar microstrip structure. The auxiliary basis functions are constructed as superposition of point-like current elements located on rectangular grids which reproduce the same far field as generated from the original basis functions. Then it is able to employ the fast Fourier transform technique to speed up the matrix vector multiplication required by the iterative solver. The resultant linear systems are then preconditioned by the symmetric successive over relaxation technique to further accelerate iteration. Compared to the previous scheme, the proposed algorithm makes a reduction in both the computational complexity and the storage requirement to attain the same precision.