Printed structures, in the form of a single printed antenna (printed dipole, patch, etc.) or an array of printed antennas on planar and cylindrical grounded dielectric slabs, are investigated. Full-wave solutions based on the hybrid method of moments (MoM)/Green’s function technique in two different domains, the spectral and the spatial domains are used to analyze these types of geometries. Several numerical problems, encountered in the evaluation of both the spectral and spatial domain integrals are addressed and solutions for these problems are presented. Among them the two important ones are: (1) The infinite double integrals which appear in the asymptotic parts of the spectral domain MoM impedance matrix and the MoM excitation vector elements for planar grounded dielectric slabs are evaluated in closed-form in this thesis, resulting an improved efficiency and accuracy for the rigorous investigation of printed antennas. (2) In the space domain MoM solution of printed structures on planar grounded dielectric slabs, an accurate way of treating the singularity problem of the self-term and overlapping terms as well as the MoM excitation vector is presented along with a way to halve the order of space domain integrals by employing a proper change of variables and analytical evaluation of one of the integrals for each double integral. Finally two different studies which use these improved methods are presented in order to asses their accuracy and efficiency: (1) Investigation of scan blindness phenomenon for finite phased arrays of printed dipoles on material coated electrically large circular cylinders, and its comparison with the same type of arrays on planar platforms. In this study effects on the scan blindness mechanism of several array and supporting structure parameters, including curvature effects, are discussed. (2) A discrete Fourier transform (DFT) based acceleration algorithm is used in conjunction with the generalized forward backward method (GFBM) to reduce the computational complexity and memory storage requirements of the aforementioned full-wave solution method for the fast analysis of electrically large finite phased arrays of microstrip patches. As a result both the computational complexity and memory storage requirements are reduced to O(N) (of order N), where N is the number of unknowns.