The Finite Tubular Antenna in a Warm Plasma

A cylindrical dipole antenna, immersed in a warm homogeneous and isotropic plasma and driven at the center by a delta‐function voltage generator, is treated as a boundary value problem. The current on the antenna is determined and found to consist of two parts: a slowly varying component that varies like the current on an antenna in a cold medium, and an oscillating component. The spatial periodicity of the oscillatory component is of the same order as that of the surface waves launched on an infinite tube containing and surrounded by warm plasma. If the antenna is driven well above the plasma frequency, the oscillatory portion of the current is negligible, while if it is driven at slightly above the plasma frequency, the oscillatory portion of current is dominant. It is found that a radiation resistance calculation made by using a current distribution valid only for an antenna in a cold environment can be incorrect when applied to an antenna in a warm plasma.