Ultra-Wideband Electromagnetic Pulse Propagation through Causal Media
Technical Report,15 Dec 2012,14 Dec 2015
RESEARCH FOUNDATION OF STATE UNIVERSITY OF NEW YORK New Paltz United States
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When an electromagnetic pulse travels through a dispersive material each frequency of the transmitted pulse changes in both amplitude and phase, and each frequency at its own rate. As a consequence, broadband pulses propagating in dispersive material experience significant amplitude distortion and changes in pulse velocity. Asymptotic analysis of the exact integral representation of the propagated field, which utilizes the full causal dispersion relation of the dispersive material, provides acomplete far-field description of the propagated pulse. In 1975, Oughstun and Sherman utilized asymptotic methods to show that in a dielectric nonconducting material the low-frequency component of the propagated field, the so-called Brillouin precursor, has a peak amplitude that decays algebraically with propagation distance as the inverse square root of propagation distance, whereas other pulse components decay exponentially.