High Frequency Electrical Oscillations in Cavities

TL;DR

This paper investigates high-frequency oscillations in conducting cavities, revealing limitations of classical electromagnetism and proposing extended equations to better predict electromagnetic behavior at high frequencies.

Contribution

It introduces an extended modeling framework that accounts for non-zero divergence regions in electric fields at high frequencies, improving prediction accuracy.

Findings

Classical Coulomb's law and Maxwell's equations are insufficient at high frequencies.

Fast signal variations create sinks and sources in the electric field.

The extended model captures non-zero divergence regions, enhancing electromagnetic predictions.

Abstract

If the interior of a conducting cavity (such as a capacitor or a coaxial cable) is supplied with a very high-frequency electric signal, the information between the walls propagates with an appreciable delay, due to the finiteness of the speed of light. The configuration is typical of cavities having size larger than the wavelength of the injected signal. Such a non rare situation, in practice, may cause a break down of the performances of the device. We show that the classical Coulomb's law and Maxwell's equations do not correctly predict this behavior. Therefore, we provide an extension of the modeling equations that allows for a more reliable determination of the electromagnetic field during the evolution process. The main issue is that, even in vacuum (no dielectric inside the device), the fast variation of the signal produces sinks and sources in the electric field, giving rise to zones where the divergence is not zero. These regions are well balanced, so that their average in the domain is zero. However, this behavior escapes the usual treatment with classical electromagnetism.