GPR(Ground Penetrating Radar) is a high resolution geophysical technique and a non-destructive technology to utilize in detecting the surface in which has the buried objects and structures such as ground layers, landmines, roads and concrete foundations. A horn antenna has better gain enhancement in same frequency range as compare with other GPR type antennas and it is suitable for demining process. In this paper, designing the pyramidal horn antennas calculated from flare angel formula at thirteen flare angle values and making the GPR-scenario with the chosen pyramidal horn design among thirteen designs have been presented by using ANSYS Electronic Desktop 2018, HFSS software.