研究目的
To establish a relationship between the S-parameters of a measured system and the properties of the permittivity and permeability extracted from the S-parameters using the Nicolson-Ross-Weir method, and to determine the conditions under which metamaterials exhibit double-negative properties.
研究成果
The study derives relationships between the measured S-parameters of an engineered material and the permittivity and permeability of the material using the Nicolson-Ross-Weir method. It identifies the conditions under which the extracted material properties may be associated with a lossless material and the relationship between the signs of the real and imaginary parts of the permittivity and permeability. Although the expressions are only truly valid when the material is lossless, they can be used to understand and predict the behavior of engineered materials with low to moderate loss.
研究不足
The analysis is only valid for lossless structures, though it can still be used to understand and predict the behavior of engineered materials with low to moderate loss. The method relies on closed-form expressions that may be too complicated to deduce simple relationships for general materials.
1：Experimental Design and Method Selection:
The study uses the Nicolson-Ross-Weir (NRW) method for measuring the permittivity and permeability of homogeneous, isotropic materials. The method is robust to most common sources of experimental error and utilizes closed-form expressions for the desired material properties computed from measured S-parameters.
2：Sample Selection and Data Sources:
The study considers engineered materials such as polymer composites with magnetic inclusions, carbon nanotube films, and composite layered dielectrics. It also examines metamaterials and metamaterial elements used in novel antennas.
3：List of Experimental Equipment and Materials:
The study involves simulations and experiments using materials like metallic elements, polymer composites, and carbon nanotube films. Specific equipment includes a vector network analyzer for S-parameter measurements.
4：Experimental Procedures and Operational Workflow:
The NRW method is applied to measure the S-parameters of material samples under specified illumination conditions. The method involves measuring the reflection from and transmission through a homogeneous sample of isotropic material.
5：Data Analysis Methods:
The study analyzes the S-parameters to predict the behavior of the extracted material parameters, focusing on the conditions under which the material parameters may be interpreted as arising from a lossless homogeneous material.
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