To increase the bandwidth of a microstrip antenna, while providing it with a protective outer layer, a structure comprised of two or three stacked radiating elements with several dielectric layers can be employed [1]. The focus of this paper is a method developed to compute the geometric parameters of this type of antenna, coaxially fed, containing up to three stacked conductors and dielectrics. This method involves computing, in the spectral domain, the necessary Green's functions, then determining the currents using an integral equation solved by a method of moments. From the radiator surface current values, we deduce the antenna's principal characteristics: input impedance, radiation pattern, etc. This method enabled determination of the geometric parameters of an antenna with two square, centered radiating elements and a protective layer. The theoretical and experimental results obtained around 1.6 GHz and 11 GHz are very encouraging. The differences between the theoretical and measured curves can be attributed to an insufficient number of modes in the description of the current.