Fast electromagnetic modeling of multilayer microstrip antennas and circuits

Rigorous full-wave electromagnetic modeling techniques play a significant role in the design of integrated circuits (ICs). The integral equation-based method is very attractive to deal with the ICs in a multilayer medium environment.; In this thesis, the method of moments (MoM) solution of multilayer microstrip antennas and circuits is presented. The multilayer Green's functions are evaluated by the discrete complex image method (DCIM). The surface-wave contribution is extracted recursively by a novel multilevel contour integral in the complex k_ρ plane. An interpolation scheme is employed to further reduce the computer time to calculate the Green's functions. The higher-order interpolatory basis functions defined on curvilinear triangular elements are applied. The curvilinear triangular elements provide great flexibility to discretize arbitrary shapes. The higher-order basis functions offer a better convergence rate than does the lower-order ones.; To achieve the fast frequency sweep, the model-order reduction technique is incorporated into this MoM analysis, in which the asymptotic waveform evaluation (AWE) is employed to obtain the Padé approximant at an expansion point. A binary search scheme is developed to automatically determine locations of expansion points.; To handle large-scale problems, two fast algorithms have been applied. One is the fast Fourier transform (FFT) accelerated algorithm. This method can be traced back to the well-known conjugate gradient FFT (CGFFT) method, which is restricted to the uniform discretization. To overcome this limitation, the adaptive integral method (AIM) is proposed, which retains the advantages of the CGFFT method as well as the excellent modeling capability offered by the triangular elements. The other fast algorithm is the multilevel fast multipole algorithm (MLFMA), which is combined with the DCIM for an efficient analysis of microstrip structures. Both of the algorithms reduce the computational complexity to O(N log N).; With these techniques together, a fast integral equation solver for microstrip structures in multilayer media is developed. Examples of circuits and antennas are presented to demonstrate the accuracy and efficiency of this solver.