Thin-wire antennas in the presence of a perfectly-conducting body of revolution

Abstract

A new numerical method for evaluating electromagnetic field, current distribution and input impedance of thin axial antennas in the presence of a perfectly conducting body of revolution is presented. Two particular cases, an axial dipole antenna near a conducting spheroid (prolate and oblate, including sphere) and near a solid truncated cone (including solid cylinder) are analysed. The actual body of revolution is replaced by an equivalent interior system of fictitious sources, axial arrays of Hertzian dipoles and magnetic ring currents. The moments of these sources are then adjusted to match boundary conditions on the surface of the body, while forthe current distributions on the antenna conductors Hallen's type integral equations are derived. The system of integral equations obtained is solved numerically by the point matching methodwith the polynomial approximation for distributions of antenna currents. The solution is numerically optimized due to the number and locations of fictitious sources. Some numerical results for antenna input impedance and cimomotore force (c.m.f.) are presented.