The current period of the mobile communications is characterized by a spectacular growth of the demand in all the types of environments, not only in density urbanized cities as suburban and rural. The planners of these systems need efficient and economically viable tools for the design of these systems. The main goal of good planning is a good coverage, and one of the most adopted quality indicators is the path loss of propagation. The mostly used deterministic technique for calculation it in strongly built micro-cells is the tracing of rays, whether the method of the images or the method of launching of rays. This work presents a detailed formularization of the method of launching of rays and of the asymptotic methods which have been used in order to calculate the electromagnetic fields (direct, reflected and diffracted) which allow to calculate the Path Loss of Propagation. Besides it this shown the used method of space discrimination, which was employed to speed up the calculation. The methodology proposal was implemented in computer program and is presented some studies of case for specific environments.