The Effect of Non-Uniform Conductivity on Radiation Characteristics of a Monopole Plasma Antenna

This study examines the effects of the tapered conductivity of plasma in a surface-wave excited plasma antenna on its radiation characteristics including resonant frequency, bandwidth, gain and input impedance. It is observed that if the plasma density in a uniform plasma column is considerably smaller than the equivalent plasma density of copper the resonant length of the plasma antenna is smaller than its equivalent metallic antenna. The results also indicate that a tapered conductivity distribution along the column (which can be formed in a surface-wave excited plasma) decreases the resonant length of the antenna up to around 20 % in this study. It is shown that a tapered conductivity plasma antenna has also a slightly wider bandwidth. However, these advantages are achieved at the cost of lower radiation gain, which is due to higher loss in the plasma column.