Electromagnetic Waves Scattering by Irregular Impedance Vibrators in Free Space

Abstract

Variation in the cross section and (or) surface impedance along a vibrator may serve as additional parameters for the formation of preassigned electrodynamic characteristics of cylindrical vibrator antennas. For example, the broadbandedness of a biconical vibrator whose arms are two cones with vertices directed to the center is much larger than that of a vibrator with constant radius. Since pioneering work by Schelkunoff [1], antennas of such configurations have attracted the attention of many investigators (see, for example, [2–6]). Vibrators with variable surface impedance, yielding additional possibilities for controlling the characteristics of antennas of fixed geometric size, take a special place among thin impedance vibrators [7–12]. We will not analyze the methods employed for solving problems described in the above-mentioned publications, but simply note that they are devoted to the investigation of radiating characteristics (both theoretical and experimental) of vibrators excited at the center by concentrated EMF. However, for the analysis of receiving antennas it is necessary to know the induced current in a scattering vibrator excited by an incident electromagnetic wave. This problem is also important for the investigation of scattering by material bodies having complex shapes ([18] in Chap. 3).