On the Current Induced within an Infinitely Long Circular Cylinder (or Wire) by an Electromagnetic Wave

Abstract

The current induced by a harmonic electromagnetic plane wave in an infinitely long wire is discussed. Two methods of calculating this current for a wire situated in vacuum will be compared: 1) one by Mohr [1] and 2) a direct calculation, which is given in Section II of this paper. Mohr's method 1) utilizes transmission line theory and the case of perpendicular incidence discussed in Jordan's book [2]. In the direct method 2) only Maxwell's equations and boundary conditions are used. When the direct method is presented in Section II, the wire is assumed to be situated in an arbitrary infinite homogeneous medium, not necessarily in a vacuum. In fact the direct method allows also the thickness and the material of the wire to be arbitrary, and so any infinitely long circular cylinder can be considered. It seems that the currents determined by Mohr's method and the direct method have roughly the same order of magnitude (at least), if the electromagnetic wave has a high-altitude-EMP frequency and is incident on a copper wire whose radius is less than about 1 cm and the angle between the line and the direction of propagation of the wave is above 45 ° . The agreement between Mohr's method and the direct method is better, the more perpendicular the incidence, the lower the frequency, or the smaller the radius of the wire.