Design And Application Of Planar Low-loss Zero-index Metamaterials

As a metamaterial with zero equivalent refractive index,zero-index metamaterial has the properties of infinite phase velocity and wavelength,so the whole wave will not experience any spatial phase delay after passing through the zero-index metamaterials.This unique feature has led to significant advantages in manipulating electromagnetic waves,so it has potential applications in directional antennas,compact resonators,switches,attenuators,curved waveguides,unidirectional devices,invisible cloaks and perfect absorbers.In this paper,a planar low-loss zero-refractive metamaterial based on a single-board is designed.According to the relationship between its electric plasma frequency and magnetic plasma frequency,a general approach for controlling low-loss near-zero refraction is proposed.The metamaterial is mainly composed of the in-plane and through-plane wires,and can achieve zero and negative refraction in the frequency range of 8-12 GHz.And it can exhibit low-loss zero-refraction in the frequency range of 10.72-11.4 GHz.Based on the influence of the unit structure on the plasma frequency,the electric plasma frequency and magnetic plasma frequency model are established,which provides a theoretical basis for designing broadband low-loss zero-index metamaterials.Based on the unique properties of zero-index metamaterials in manipulating electromagnetic waves,we designed a high-orientation terahertz circulator and a high-performance electromagnetic-wave switch.We designed a terahertz circulator based on zero-index metamaterials.The terahertz circulator has a callback loss(|S11|)greater than 10 dB,an insertion loss(|SS21|)less than 5 dB,an isolation(|S31|)is more than 16 dB,and the directionality is higher than 14 dB,achieving good unidirectional circuit transmission property,which provides a new way to develop terahertz circulators.The electromagnetic-wave switch designed in this paper realizes the switching characteristic by controlling the permittivity of the dielectric defect in the zero-index metamaterial,and can realize the excellent performance electromagnetic-wave switch in the frequency range of 10.5-11.54 GHz,with a relative transmission ratio up to 97.8%.