Resumo

LEY-KOO, E.; TORRES-BUSTAMANTE, H.  e  GONGORA T., A.. Spherical symmetry breaking in electric, magnetic and toroidal multipole moment radiations in spherical toroidal resonant cavities and optimum-efficiency antennas. Rev. mex. fis. [online]. 2021, vol.67, n.2, pp.174-179.  Epub 16-Fev-2022. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.67.174.

This Letter reports the breaking of the spherical symmetry in the complete electromagnetic multipole expansion when its sources are distributed on spherical toroidal surfaces, identifying the specific geometrical and physical changes from the familiar case of sources on a spherical surface. In fact, for spherical toroids defined by concentric spherical rings and symmetric conical rings, the boundary conditions at the latter are not compatible in general with integer values for the orbital angular momentum label of the multipole moments: the polar angle eigenfunctions become Legendre functions of order λ and associativity m represented as infinite series with a definite parity, and their complementary associated radial functions are spherical Bessel functions of the same order λ. Consequently, the corresponding multipole sources for the electric, magnetic and toroidal moments and their connections are identified within the Debye formalism, and the appropriate outgoing wave Green functions are constructed in the new basis of eigenfunctions of the Helmholtz equation. Our familiarity with the exact solutions, for the cases of the complete sphere and of cylindrical toroids, allow us to give a preliminary account of the electromagnetic fields for the spherical toroids via the integration of their sources and the Green function for resonant cavities and optimum-efficiency antennas.

Palavras-chave : Electromagnetic multipole moment expansion; symmetry breaking from sphere to spherical toroids; longitudinal; poloidal and toroidal sources and fields for electric; magnetic and toroidal moments; and their connections in Debye formalism; Green functions for resonant cavities and optimum-efficiency antennas.

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