FDTD analysis of a plasma whip antenna

Plasma antenna technology employs ionized gas enclosed in a tube (or other enclosure) as the conducting element of an antenna. Characteristics of the plasma antenna largely depend on the behavior of an electromagnetic wave propagating in plasma. But few analytical solutions of the plasma antenna have been carried out because the permittivity of plasma varies significantly with frequency. In an effort to model the plasma medium accurately and predict the characteristics of such antenna, attention has been focused on use of the finite-difference time-domain (FDTD) method. A plasma whip antenna is investigated by use of the frequency-dependent finite-difference time-domain ((FD)/sup 2/TD) formulation (Luebbers, R.J. et al., IEEE Trans. Electromagnetic Compatibility, vol.32, p.222-7, 1990; IEEE Trans. Antennas and Propag., vol.39, p.29-34, 1991). Key aspects of the (FD)/sup 2/TD implementation are discussed. The plasma frequency exercises a more significant effect on the deviation of the resonant frequency of the plasma antenna than the collision frequency while the latter affects significantly the magnitude of return loss. Numerical results show that the plasma antenna really offers a promising alternative to the traditional metal antenna when the plasma frequency is much higher than the operating frequency.