基于蘑菇型结构的双入射超宽带复合媒质材料设计与分析

Design and analysis of double incidence metamaterials composed of mushroom-shaped structure

通过设计一定的单元结构,可以实现超宽带人工电磁材料.基于蘑菇型金属结构,提出了一种同时具有左右手通带无缝结合的超宽带双入射型复合媒质材料结构单元.该结构由嵌入到介质板的两个反向对称的蘑菇型金属结构组成,能够同时引发电谐振和磁谐振而得到左手通带.通过利用CST软件仿真、等效电磁参数提取、折射率计算以及建立等效磁谐振电路模型等方法,分析验证了该结构的双入射特性和左手特性.仿真结果表明,在电磁波垂直于介质板和平行于介质板入射两种情况下,在X波段均表现出左手通带特性,并具有1 GHz以上的左手带宽.当电磁波垂直于介质板入射时,在7.2 GHz-9.3 GHz频段为右手通带,在9.3 GHz-11 GHz频段为左手通带;当电磁波平行于介质板入射时,在7.0 GHz-9.0 GHz频段为右手通带,在9.0 GHz-10 GHz频段为左手通带.在两种情况下分别于9.3 GHz与9.0 GHz处得到了零折射率,从而构造了一种正-零-负复合媒质材料,实现了具有3 GHz带宽的双入射超宽带平衡结构.

An ultra-wide band metamaterial may be achieved via the design of some structures. A metamaterial unit supporting two- dimensional （2D） incident electromagnetic （EM） wave is proposed based on the mushroom type-structures, which has an ultra-wide band with seamlessly combined band of right-handed and left-handed pass-bands. This unit is designed by setting two reverse symmet- rical mushroom-shaped strips on each side of the dielectric substrate respectively, and the electric resonance and the magnetic resonance could be excited simultaneously. With CST software, the right-handed and left-handed properties are analyzed and verified by means of spectrum analysis, effective parameters of permittivity, permeability and index of refraction extracted from S parameters, and equivalent magnetic resonance circuits. The results show that the structure can present left-handed properties with 1 GHz left-handed pass-band in X waveband, either EM wave is incident in the direction perpendicular or parallel to the plane of the substrate. When the EM wave is incident in the direction perpendicular to the substrate, the right-handed and the left-handed pass-bands appear at 7.2 GHz--9.3 GHz and 9.3 GHz--11 GHz respectively; while when the EM wave is incident in the direction parallel to the substrate, the right-handed and the left-handed pass-bands appear at 7.0 GH--9.0 GHz and 9.0 GHz--10 GHz respectively. It also shows that the zero indexes of refraction occur at 9.3 GHz and 9.0 GHz in the tow instances above. So that a plus-zero-negative metamaterial is constructed and a 2D incident balanced-structure with an ultra-wide band of 3 GHz is achieved.