A reactance theorem
Abstract
A formula is derived for the frequency derivative of the input reactance of any linear passive timeinvariant electromagnetic system. It consists of five terms, each of which is identifiable uniquely with one of the following five physical attributes of the system: timeaverage stored magnetic energy, timeaverage stored electric energy, radiation, dispersion by the medium, and dissipation by the medium.
 Publication:

Proceedings of the Royal Society of London Series A
 Pub Date:
 February 1977
 DOI:
 10.1098/rspa.1977.0018
 Bibcode:
 1977RSPSA.353....1R
 Keywords:

 Electromagnetic Wave Transmission;
 Linear Systems;
 Reactance;
 Electromagnetic Fields;
 Electromagnetic Properties;
 Electromagnetic Radiation;
 Energy Dissipation;
 Lossless Materials;
 Radiation Effects;
 Theorems;
 Wave Dispersion;
 Electronics and Electrical Engineering