The cylindrical antenna as a probe for studying the electrical properties of media

When a base-driven cylindrical monopole (or center-driven dipole) is immersed in an arbitrary medium, the electric and magnetic fields on its surface depend not only on its length and radius but also on the effective conductivity and permittivity of the medium. These fields can be explored and measured with small probes designed to travel along the cylindrical surface of the antenna. The interpretation of the observations depends on the availability of a general theory that correctly describes the distributions of current and charge on the conductor. The results of a new theory that is valid for electrically thin monopoles up to
5\lambda/8
(dipoles up to
5\lambda/4)
in length over all practical ranges of conductivity and permittivity of the ambient medium, including those characteristics of under- and overdense cold plasmas, are described together with their experimental verification.