Thework carried out is the study and executionwhosemain ideawas to verify the feasibility of using a coaxial cable of theCELLFLEX 1/2 (center dot center dot) model to obtain a low-cost antenna applied to 5G technology operating at 3.5 GHz frequency, according to current regulations. The computer simulations were performed in the commercial software CST STUDIO SUITE, where rectangular geometry apertures were made in the center of the coaxial cable in order to analyze the behavior of the field radiated by the lambda/2 aperture, which corresponds to half the wavelength in relation to the frequency of interest to be analyzed, given by the Babinet Principle. From then onwards, some variations were made in the dimensions of the aperture, thus observing its response to the radiated field, in the case of the reflected wave, as a function of the applied frequency. Thus, a 3D computational modeling of an aperture antenna typewas performed, inwhich each simulated result, the reflection coefficient (gain), and the bandwidth that meet the characteristics of a practical application antenna were analyzed. A bandwidth of 115.8 MHz was obtained considering for an ideal antenna reflection coefficient of -10 dB, a reflection coefficient of -13.126 dB for the exact 3.5 GHz, with a deviation to a maximum reflection coefficient of -21,679 dB at 3.5411 GHz. It is concluded then, the need to search for results closer to the frequency of interest, seeking to obtain more and more optimized parameters.