A surface-wave driven plasma antenna has been built. An exponential model of the surface current distribution has been proposed to calculate the radiation pattern of the plasma antenna. The results show that the plasma density decreases exponentially with the axial length. The magnitude of the imaginary part of the surface wave vector shows similar exponentially decaying profile with the plasma density under normal conditions, while the real part of the wave vector remains almost constant. The surface current distribution shows a traveling wave mode with exponentially decaying magnitude. The calculated radiation pattern of a typical “8” figure fits the experimental values well using the proposed surface current distribution model. The radiation pattern is broadened when the input RF power decreases.