We investigated some important plasma antenna parameters, such as the transmission characteristics of a microwave propagating along the cylindrical symmetric plasma antenna, dispersion relations, radiation pattern and gain. By analyzing the dielectric constant of the tube material, the outer and inner radius, the density of the plasma and the collision frequency, we found that to minimize the attenuation of wave propagation along the plasma antenna, one should increase the density of the plasma, decrease the collision frequency, increase the radius of the plasma, increase the thickness of tube，and decrease the dielectric constant. We also calculated the radiation pattern of the plasma antenna and the change of gain under different conditions. These results are useful for the design of plasma antenna.