Radiation Limit: Introducing an Energy-Density Framework for Cylindrical EM Systems

This work presents a generalized framework for analyzing transitions between quasi-stationary and propagative regimes in cylindrical electromagnetic (EM) systems. Starting from Abraham and Schelkunoff’s principles, it yields that the dynamic behavior of cylindrical capacitors and inductors depends uniquely on spatiotemporal energy density. The proposed approach, based on Maxwell's equations and Hertz's method, provides a versatile tool for complex cylindrical geometries. These results offer insights into energy confinement and establish a universal framework for next-generation EM technologies, e.g. antennas, metasurfaces, THz metamaterials, ultra-high-Q resonators, and wireless power systems