The numerical solution of complex electromagnetic problems via heterogeneous solution methods is proposed. This book presents a hybrid technique, which combines the desirable features of the method of moments (MoM) and wavelet transform. This technique is used to analyze large-scale problems. The discrete wavelet, and wavelet packet transforms (DWT, WPT) are used to sparsify the method of moments (MoM) matrix for large scale problems. which results in a great improvement in the computer storage size and also a reduction in the computational time.An algorithm based on the adaptive basis functions/ diagonal moment matrix (ABF/DMM) technique is used to analyze electromagnetic problems of identical elements to develop a diagonal moment matrix. The computational domain is divided into smaller and manageable sub-domains, with coupling between these sub-domains is taken into account. By independently solving each sub-domain using MoM and applying WPT, thus MoM impedance matrix is sparse. An Iterative Field Refinement (IFR) approach takes place to combine the sub-domains solutions to obtain a solution for the complete domain. So, a considerable reduction in the time and storage is achieved