This paper presents the design, simulation and construction of waveguide resonant slot antenna, for operation in the microwave range. The antenna design was done employing a software tool based on the synthesis of Taylor of one parameter and the analysis based on array and aperture models. Different parameters in the antenna design were simulated, like changes in the number of slots and in the sidelobe level. The final antenna design and the direct analysis based in the array model, has been compared with CST® Microwave Studio full wave analysis. The antenna prototype measurement gives satisfactory results and validates the implemented tool.