Current distribution and impedance of a cylindrical antenna in an isotropic compressible plasma

摘要

Current distributions for cylindrical dipoles in isotropic compressible plasmas have been determined for discrete sets of plasma temperature and densities. Coupling between the optical and plasma modes at the surface of the antenna have been accounted for, producing quite different electrical lengths than experienced in incompressible plasmas. Calculations have been made on the assumption that the normal electron velocity of the compressible plasma vanishes at the surface of the antenna. A new approximation technique has allowed simplified computer solutions for the eigenvalues determining the current distribution on the cylindrical structure. Resulting current distributions display hybrid optical-plasma characteristics for certain frequency spectra. These results clearly point out the form of the assumed current distribution for a given structure. Having obtained an approximation for the electroacoustic current distribution, calculations for the radiation resistance of an electric dipole are easily performed. Results for the radiation resistance of various lengths of the antenna are presented, illustrating the dominance of the plasma mode for certain frequency spectra. Results have also been obtained for discrete sets of plasma temperature and densities, as well as different length-to-diameter ratios of the dipole antenna. A discussion of the field structure of the optical-plasma mode is included.