具有宽带特性的超材料设计与分析*

分别提出具有宽带负磁导率特性的圆盘结构超材料和具有宽带双负特性的互联圆盘结构左手材料。对任意极化的垂直入射波,圆盘结构超材料可在8.71GHz到15.19GHz的频段上产生负的磁导率,而互联圆盘结构左手材料则可在6.04GHz到7.40GHz的频段上产生双负特性。通过有限元仿真、本构参数提取、表面电流分布计算、结构参数扫描等方法,对圆盘结构进行了详细分析。结果表明,该结构通过外加磁场激励起的电流环路构成磁谐振回路,进而获得负磁导率特性。利用无限划分的方法,分析了该结构实现宽带特性的原理,推导了等效的磁谐振频率和品质因数的计算公式,并给出其等效电路结构。通过参数扫描,分析了贴片半径、基板介电常数、损耗特性和入射角大小对负磁导率特性的影响规律。对互联圆盘结构左手材料,在提取其等效本构参数的基础上,着重分析了电响应特性,详细推导了等效电等离子体频率的计算公式。

Design and Analysis of a Broadband Metamaterial

A novel disc-shaped metamaterial with wide-band negative permeability and a connected disc-shaped broad- band left-handed metamaterial are proposed, respectively. For perpendicular incident waves with arbitrary polarization, the disc-shaped metamaterial provides a negative permeability frequency band from 8.71GHz to 15.19GHz, and the connected disc-shaped left-handed metamaterial enables a double negative property from 6. 04GHz to 7.40GHz. The disc-shaped structure is investigated by finite element method(FEM) simulation, constitutive parameter extraction, surface current distribution calculation, parameter sweep simulation. The results show that a magnetic resonate loop excited by external magnetic field can produce a negative permeability characteristic. The operating principle of its broadband characteristic is analyzed by an infinite division method. The magnetic resonant frequency and quality factor are calculated as well. Additionaly, the equivalent circuit structure is presented based on above analysis. Through the parameter sweep analysis, we estabilsh the relationship between negative permeability characteristic and associated physical factors, namely, patch radius, permittivity of substrate, loss property and incident angle. Finally, the electric responsibility of the connected disc-shaped structure is investigated in detailed, and the equations of its equivalent electric plasma frequency is deduced based on the equivalent constitutive parameter extraction.