Fast electromagnetic solver using adaptive integral method

The adaptive integral method (AIM) to accelerate iterative solution of the integral equation is described for analysis of free-space and stratified medium problems. This method employs triangular basis functions and computes the matrix-by-vector product, which arises from the method of moments (MoM) discretization of such problems, by using the fast Fourier transform (FFT). As a result, this method not only retains the excellent modelling capability offered by the triangular basis functions, but also significantly reduces the demand of computer memory and central processing unit (CPU) time. For microstrip structures in a stratified medium environment, the discrete complex image method (DCIM) is employed to efficiently evaluate the spatial domain Green's functions. Numerical results of microstrip antennas and circuits and three-dimensional scatterers in free-space are presented to demonstrate the accuracy and efficiency of this method.