Generating an electromagnetic multipole by oscillating currents

Asaf Farhi*, David J. Bergman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Based on the relation between a plane phased array and plane waves we show that a spherical current layer or a current sphere proportional to a multipole electric field and situated in a uniform medium generates the same multipole field in all space. We calculate TE and TM multipoles inside and outside the spherical layer. The l=1 TM multipoles are localized at the origin with a focal spot with full width at half maximum of 0.4λ in the lateral axes and 0.58λ in the vertical axis. The multipole fields near the origin are prescriptions for the current distributions required to generate those multipole fields. A spherical layer can couple to a multipole source since the oscillation of the electrons in the layer due to the multipole field generates the multipole field in all space, which in turn can drive the multipole currents. Exciting a multipole in a polarizable sphere or spherical layer can couple it to another polarizable sphere or spherical layer.

Original languageEnglish
Article number023857
JournalPhysical Review A
Issue number2
StatePublished - 28 Aug 2017


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