Unlimited Accumulation of Electromagnetic Energy Using Time-Varying Reactive Elements

TL;DR

This paper demonstrates that by using time-varying reactive elements, electromagnetic energy can be accumulated indefinitely from a continuous wave source, overcoming traditional steady-state energy reflection limits.

Contribution

It introduces a novel approach using time-varying reactive loads to achieve unlimited energy storage from a harmonic source, supported by analytical derivations and circuit design examples.

Findings

Time-varying reactive loads can store unlimited electromagnetic energy.

Analytical formulas for load reactance time dependence are derived.

Designs for circuits with arbitrarily controlled current evolution are proposed.

Abstract

Accumulation of energy by reactive elements is limited by the amplitude of time-harmonic external sources. In the steady-state regime, all incident power is fully reflected back to the source, and the stored energy does not increase in time, although the external source continuously supplies energy. Here, we show that this claim is not true if the reactive element is time-varying, and time-varying lossless loads of a transmission line or lossless metasurfaces can accumulate electromagnetic energy supplied by a time-harmonic source continuously in time without any theoretical limit. We analytically derive the required time dependence of the load reactance and show that it can be in principle realized as a series connection of mixers and filters. Furthermore, we prove that properly designing time-varying LC circuits one can arbitrarily engineer the time dependence of the current in the circuit fed by a given time-harmonic source. As an example, we theoretically demonstrate a circuit with a linearly increasing current through the inductor. Such LC circuits can accumulate huge energy from both the time-harmonic external source and the pump which works on varying the circuit elements in time. Finally, we discuss how this stored energy can be released in form of a time-compressed pulse.