Demonstration of Fano resonance-based miniaturized cylindrical cloaking scheme
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Demonstration of Fano resonance‑based miniaturized cylindrical cloaking scheme Sarin V. Pushpakaran1 · P. V. Vinesh1 · M. Manoj2 · Chandroth Aanandan2 · P. Mohanan2 · Vasudevan Kesavath2 Received: 28 January 2020 / Accepted: 24 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract An experimental realization of a magnetic Fano-like resonance-based cylindrical cloaking scheme in the microwave frequency regime is presented in this paper. Fano-like resonance is excited by the coupling between the background electric dipole mode and the dark magnetic resonant mode in the composite. The excitation of Fano interference patterns significantly reduces scattering from the composite at resonance in the microwave regime and hence the target becomes undetectable from backscattering measurements. Multipolar scattering theory has been used to clarify the excitation of this Fano resonance and the designed cloak is characterized using monostatic and bistatic scattering measurements inside an anechoic chamber. Keywords Electromagnetic cloaking · Fano resonance · Dogbone metamaterials · Toroidal dipoles
1 Introduction Electromagnetic scattering reduction from subwavelength structured metallic and dielectric targets is a challenging research topic over the decade. Scattering studies of magneto dielectrics have attracted a wide interest in plasmonics. M. Kerker pointed out some unusual scattering characteristics from magneto dielectrics with specific electromagnetic parameters of spheres and this conclusion is popularly known as Kerker’s paradox [1]. When an electromagnetic wave impinges on arrays of subwavelength inclusions, electric and magnetic dipoles will be created on these composites. An equal magnitude inphase excitation of electric and magnetic moments on the composite exhibits coherent forward scattering and acts like a Huygens’s source [2]. An out of phase oscillation between them results in destructive interference resulting in scattering suppression which finds application in electromagnetic cloaking [3]. The invention of metamaterials boosted the research on electromagnetic cloaking due to * Sarin V. Pushpakaran [email protected] 1
Department of Electronics, Government College Chittur, Palakkad, Kerala 678104, India
Centre for Research in Electromagnetics and Antennas, Cochin University of Science and Technology, Cochin, Kerala 682022, India
2
their unusual material parameters under plane wave excitation. J.B Pendry practically proposed the first cloaking structure using a cylindrical array of specially designed split ring resonator array [4]. An alternate technique is to use a plasmonic cover over the dielectric target to be cloaked [5, 6]. The negative permittivity offered by the outer layer effectively suppresses scattering from the dielectric target. Plasmonic cloaking could be effectively used to cloak a dipole antenna from its surroundings without deteriorating its reception characteristics [7]. But when the size of the target increases, there would be acute scattering from
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