Antennas: Theory and Practice

Return stroke transmission line model for stroke speed near and equal that of light

“…Equations (13) and (19), the fields for speed c, can also be obtained by assuming that a spherical TEM wave propagates at speed c between two concentric conducting conical surfaces with common apexes and solving for the properties of the fields in that waveguide (e.g., Schelkunoff, 1952), that result being applicable to our case of a vertical lightning channel above an infinite ground plane in the limit that the inside cone angle goes to zero and the outside cone angle goes to 180 ø. Le Vine and Meneghini (1978), using a procedure different from that of this paper, provide an exact expression for the fields due to a current wave travelling at speed c along a filament of finite length.…”

Front Matter

“…Nano-sized silver and gold metal spheres, that are resonant to light account for the beautiful colors of the Roman Lycurgus cup [43], and many stained glass windows gain their colors from such local resonances [44]. Resonant arrays of metallic split rings may lead to artifical magnetism [45], with the effective magnetic permeability taking negative values in appropriate frequency ranges [46]. Low-frequency spectral gaps were noticed by Zhikov [47,48].…”

Wideband RF Radiation from a Nonlinear Transmission Line with a Pre-magnetized Ferromagnetic Core

“…In their turn, the radiated spectral field components E(ω, k) in Eq. (1) are fully determined by directional properties of the transmit antenna and frequency composition of the signal to drive that [9]. We have come to the necessity of a detailed study of directional properties of the three antennas used in the radiation experiment.…”