Alleviating Oscillatory Approximate-Kernel Solutions for Cylindrical Antennas Embedded in a Conducting Medium: a Numerical and Asymptotic Study

We alleviate the unnatural oscillations occurring in the current distribution along a linear cylindrical antenna center-driven by a delta-function generator and embedded in a conducting medium. The intensely fluctuating current arises as a small-$z_0$ asymptotic (or numerical) solution of the classical integral equations of antenna theory, for a cylindrical dipole of infinite (or finite) length, where $z_0$ is the discretization length. To alleviate the oscillations, we employ an appropriate effective current further to the recent remedy of oscillations attained for a perfectly conducting linear cylindrical antenna of finite length for the case where the surrounding medium is free space. We derive asymptotic formulas for the infinite antenna which are put to numerical test, and point to the physical significance of the effective current which transcends a mere computational device.