High Frequency Electrical Oscillations in Cavities

Abstract

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.

Highly Directive Biconic Antennas Embedded in a Dielectric

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The Space-Time Metric Outside a Pulsating Charged Sphere

“…It is known that the trace of G αβ is equal to −R. This suggest interesting relations between the scalar curvature and the trace of T αβ (see (17) for the case of the metric (4)).…”

“…If we want the information to travel at finite speeds comparable to that of light, it is necessary to assume regions of space (also in a perfect vacuum) where div E = 0, even if there are no physical charges. The elementary case of a capacitor consisting of two infinite parallel plates represents a viable exercise to verify this statement [16,17].…”

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