Electromagnetic radiation in a time-varying background medium

Journal article (2009)

Authors

N.V. Budko Electromagnetism
Research Group
Electromagnetism
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Published Date

2009

Language

Undefined/Unknown

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Research Group

Electromagnetism

Abstract

Analytical solutions are presented for the electromagnetic radiation by an arbitrary pulsed source into a homogeneous time-varying background medium. In the constant-impedance case an explicit radiation formula is obtained for the synchronous permittivity and permeability described by any positive function of time. As might be expected, such a medium introduces significant spectral shifts and spatiotemporal modulation, which are analyzed here for the linear and exponential time variations of the medium parameters. In the varying-impedance case the solution is obtained for the fourth-order polynomial time dependence of the permittivity. In addition to the spectral shifts and modulation this spatially homogeneous medium scatters the field introducing causal echoes at the receiver location.