| This thesis uses a modified Finite-Difference Time-Domain (FDTD) method to examine several wide and dual band antenna structures. The FDTD method is a finite difference approximation to Maxwell's equation that is solved in the time domain. Frequency domain results are obtained by taking the Fourier transform of the time-domain result. Recent advances in the FDTD method such as the Convolutional Perfectly Matched Layer (CPML) were necessary for such analysis of certain structures and have been used for simulation in this thesis. Some improvements in the implementation of the boundary conditions and in the CPML implementation have been documented and the new Floating Perfectly Matched Layer (Floating PML) has been introduced. The historical and mathematical development of the FDTD method is also discussed.; The code itself is written in object-oriented C++ and has been partially optimized for speed. It has been written so that microstrip and stripline structures are particularly easy to implement. Because the code fully implements Maxwell's equations, the radiation characteristics of antennas are correctly modeled when designing microstrip structures. The code has been verified with simple to more complicated antenna structures such as microstrip-fed dielectric resonator antennas (DRA). (Abstract shortened by UMI.)... |
