Velocity of Energy Characteristics of Electromagnetic Waves Emitted by Hertz Dipole Excited by Gaussian Pulse

Abstract

The analysis of the velocity of the Poynting vector and the energy density of electromagnetic waves emitted by the Hertz dipole excited by the Gaussian pulse are performed analyzing the motion of causal and extreme surfaces. The study of these characteristics opens up the possibilities of velocity determination of individual parts of pulses, such as slopes, not just causal surfaces. The mathematically confirmed view of pulse narrowing or widening, its shape changes, the ratio of pulse velocity to the light velocity c, is formulated based on the lack of energy transfer through the causal surface. We show that the electromagnetic wave of the Hertz dipole moves with the light velocity c only at large distances from the source, asymptotically approaching c. Due to this study we may say that “light velocity c is the velocity of an electromagnetic wave in a vacuum at long distances from the source.” This additive “at long distances from the source” is not important for light waves with a micrometric wavelength, but it is important from a natural and conceptual point of view and for radio waves. The obtained results shed light on physical processes near the Hertz dipole, that have no explanation due to the lack of information about the directions and velocities of the Poynting vector and the energy density of electromagnetic waves near the dipole.