The Excitation of Resonances by a Dipole Antenna Inside a Hollow Cylindrical Plasma

The problem of the excitation of resonances by a dipole antenna inside a hollow cylindrical plasma is examined. The plasma is assumed to be cold, uniform, isotropic, and lossy. A transversely oriented point electric dipole antenna lying on the axis of the cylindrical plasma is the source under consideration. For a thin and lossless plasma, resonances are found to occur at the two frequencies corresponding to dipolar resonances in a hollow cylindrical plasma as derived earlier by, for example, Kaiser and Closs, and Vandenplas. In addition, there is also an antiresonance at the plasma frequency. The radiation resistance and radiation patterns of the plasma-covered dipole are presented to show the effects of the radii of the plasma tube, the signal frequency and the collision frequency. The possible practical implications of the present study as pertaining to the improvements of reentry communication and the excitation of plasma resonances in ionospheric irregularities are discussed.