Definitive Conditions on Maxwell's Tangential E or H for Solutions to His Equations Inside a Bounded Region

• Published in: Communications on pure and applied mathematics Vol. 72; no. 10; pp. 2196 - 2230
• Main Authors: Cappell, Sylvain E., Miller, Edward Y.
• Format: Journal Article
• Language: English
• Published: New York John Wiley and Sons, Limited 01.10.2019
• Subjects: Charge density; Lattices; Magnetic permeability; Mathematical analysis; Matrix methods; Maxwell's equations; Natural algorithms; Riemann manifold; Smooth boundaries; Tensors; Waveguides
• ISSN: 0010-3640; 1097-0312
• DOI: 10.1002/cpa.21821

Let U be a connected, closed, bounded region in ℝ3 with smooth boundary 𝛛U. Consider Maxwell's equations on U for smooth fields and smooth sources, which are time harmonic, i.e., the fields E,B,H,D and the current density J and charge density ρ on U temporally varying as e−iωt. We assume ω ≠ 0; when it is real, ω is the frequency of the pure oscillation; when ω is not real, one has exponentially decreasing or increasing oscillatory fields. We treat very general electric permittivity ɛω and magnetic permeability μω, which may both depend upon ω. Both can be arbitrary, time‐independent, smoothly varying with position and described by complex Hermitian tensors subject only to weak positivity conditions specified below at each point of U. In this paper necessary and sufficient conditions are found for the tangential components, ET or HT on 𝛛U, to be realized by solutions of Maxwell's equations on all of U with these given sources J, ρ in the time‐harmonic realm with ω ≠ 0. Also, all solutions E,H on U with specified ET, HT, respectively, satisfying the necessary finite‐dimensional conditions are derived by an effective natural algorithm. In the electric ET case, the positivity condition is this: the complex Hermitian matrix μω(p) is to be positive definite while only the real part of ɛω(p), i.e., Re(ɛω(p)), necessarily real symmetric, need be positive definite. In the magnetic‐type HT case, the two roles are reversed. These positivity conditions are more general than those commonly considered. In the final section Maxwell's equations and all the present results are reformulated yet more generally in a context of compact, smooth, Riemannian manifolds with boundary. Sample examples include periodic lattices and wave guides. © 2019 Wiley Periodicals, Inc.