A Theory for Electromagnetic Radiation and Coupling
- Gaobiao Xiao
Gaobiao Xiao
Shanghai Jiaotong University, Shanghai Jiaotong University, Shanghai Jiaotong University, Shanghai Jiaotong University, Shanghai Jiaotong University
Corresponding Author:[email protected]
Author ProfileAbstract
A theory for analyzing the radiative and reactive electromagnetic
energies of a radiator in vacuum is presented. In vacuum, the radiative
electromagnetic energies will depart from their sources and travel to
infinity, generating a power flux in the space. However, the reactive
electromagnetic energies are bounded to their sources. They appear and
disappear almost in the same time with their sources, and their
fluctuation also causes a power flux in the space. In the proposed
theory, the reactive electromagnetic energies of a radiator are defined
by postulating that they have properties similar to the self-energies in
the charged particle theory. More importantly, in addition to a main
term of source-potential products, the reactive energies contain a
special energy term which will last to exist a short time after the
sources disappear. This oscillating energy is related to the electric
displacement and the vector potential, and seems to be responsible for
energy exchanging between the reactive energy and the radiative energy
in the radiation process, performing like the Schott energy term. As the
Poynting vector describes the total power flux density related to the
total electromagnetic energy, it should include the contributions of the
propagation of the radiative energies and the fluctuation of the
reactive energies. The mutual electromagnetic couplings between two
radiators are also defined in a similar way in which the vector
potential plays a central role. The reactive electromagnetic energies
can be evaluated with explicit expressions in time domain and frequency
domain. The theory is verified with the Hertzian dipole and numerical
examples.