A plasma antenna is a radiating device partially composed of plasma instead of metals or dielectrics, and as a result, it exhibits reconfigurable properties unlike conventional metallic antennas. By tuning the plasma discharge parameters, e.g., the plasma density, the antenna properties can be changed dynamically. In this work we report on recent numerical investigations into the characteristics of plasma antennas as a function of the plasma discharge parameters. We have used ADAMANT (Advanced coDe for Anisotropic Media and ANTennas) - a full-wave numerical tool based on integral equations - to assess the role played by plasma discharge parameters in shaping the gain function, and the antenna input impedance