Instantaneous Radiation from Time-Varying Electric and Magnetic Dipoles

Abstract

Radiation from magnetic and electric dipole moments is a key subject in theory of electrodynamics. Although people treat the problem thoroughly in the context of frequency domain, the problem is still not well understood in the context of time domain, especially if dipole moments arbitrarily vary in time under action of external forces. Here, we scrutinize the instantaneous power radiated by magnetic and electric dipole moments, and report findings that are different from the conventional understanding of their instantaneous radiation found in textbooks. In contrast to the traditional far-field approach based on the Poynting vector, our analysis employs a near-field method based on the induced electromotive force, leading to corrective terms that are found to be consistent with time-domain numerical simulations, unlike previously reported expressions. Beyond its theoretical value, this work may also have significant impact in the field of time-varying metamaterials, especially in the study of radiation from subwavelength meta-atoms, scatterers and emitters that are temporally modulated.

References in corpus (4)

• Parametric amplification and bidirectional invisibility in PT-symmetric time-Floquet systems
• On the exact electric and magnetic fields of an electric dipole
• Instantaneous Power Radiated from Magnetic Dipole Moments
• The Reactive Energy of Transient EM Fields

Cited by in corpus (6)

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• A Generalization of the Kramers-Kronig Relations for Linear Time-Varying Media
• Photonic time crystals: Theory and applications
• Time-varying components for enhancing wireless transfer of power and information
• Primordial monopolium as dark matter