title: Quasi-Static Magnetic Field Shielding Using Longitudinal Mu-Near-Zero Metamaterials.
abstract: The control of quasi-static magnetic fields is of considerable interest in applications including the reduction of electromagnetic interference (EMI), wireless power transfer (WPT), and magnetic resonance imaging (MRI). The shielding of static or quasi-static magnetic fields is typically accomplished through the use of inherently magnetic materials with large magnetic permeability, such as ferrites, used sometimes in combination with metallic sheets and/or active field cancellation. Ferrite materials, however, can be expensive, heavy and brittle. Inspired by recent demonstrations of epsilon-, mu- and index-near-zero metamaterials, here we show how a longitudinal mu-near-zero (LMNZ) layer can serve as a strong frequency-selective reflector of magnetic fields when operating in the near-field region of dipole-like sources. Experimental measurements with a fabricated LMNZ sheet constructed from an artificial magnetic conductor - formed from non-magnetic, conducting, metamaterial elements - confirm that the artificial structure provides significantly improved shielding as compared with a commercially available ferrite of the same size. Furthermore, we design a structure to shield simultaneously at the fundamental and first harmonic frequencies. Such frequency-selective behavior can be potentially useful for shielding electromagnetic sources that may also generate higher order harmonics, while leaving the transmission of other frequencies unaffected.
authors.affiliation: Duke University, Department of Electrical and Computer Engineering, 130 Hudson Hall, Durham, North Carolina, 27708 USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Lipworth
authors.affiliation: University of Washington, Department of Electrical Engineering, Seattle WA 98195.
authors.forename: Joshua
authors.initials: J
authors.lastname: Ensworth
authors.affiliation: Duke University, Department of Electrical and Computer Engineering, 130 Hudson Hall, Durham, North Carolina, 27708 USA.
authors.forename: Kushal
authors.initials: K
authors.lastname: Seetharam
authors.affiliation: Toyota Research Institute of North America, Ann Arbor, Michigan, 48105 USA.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Toyota Research Institute of North America, Ann Arbor, Michigan, 48105 USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Schmalenberg
authors.affiliation: Toyota Central R&D Labs, Inc., Aichi, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nomura
authors.affiliation: University of Washington, Department of Electrical Engineering, Seattle WA 98195.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Reynolds
authors.affiliation: Duke University, Department of Electrical and Computer Engineering, 130 Hudson Hall, Durham, North Carolina, 27708 USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Smith
authors.affiliation: Duke University, Department of Electrical and Computer Engineering, 130 Hudson Hall, Durham, North Carolina, 27708 USA.
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Urzhumov