The problem of Gaussian beam propagation is of significant interest for many physical disciplines, including optics, geophysics, and acoustics. Individual Gaussian beams are asymptotic solutions of Helmholtz's equation. Since they are insensitive to ray transition region, several techniques based on Gaussian beam are used to evaluate high frequency EM wave equation, which overcome partially or fully the difficulties of singular regions (caustics, zero field in shadow zones). We compare two different accurate and approximate representations for the scattered electromagnetic field from canonical and complex targets, given in terms of Gaussian beam. The Gaussian beam launching technique (GBL) consist of representing the scattered field by a set of Gaussian beams which strike the target surface from where they are reflected, and also diffracted by the target edge. In the Gaussian beam summation (GBS) approach the complete wave field at a receiver is evaluated as superposition Gaussian beams concentrated close to rays emerging from the target, passing in the neighborhood of the receiver.