Analysis, design, and implementation of a reconfigurable fractal volumetric left-handed metamaterial
At the present time, one of the greatest goals to exploit the advantages of Volumetric Left-handed Metamaterials (LHM) is overcoming their very narrow operational bandwidth. This thesis proposes two schemes to efficiently solve this difficulty: 1) a mechanism which reconfigures, at will, the frequency the LHM operates at, and 2) a novel arrangement of Split Ring Resonators (SRR) based on the Sierpiński carpet fractal pattern with two SRR sizes. Reconfigurability is implemented by cutting two splits of different widths in each ring of the SRRs. These SRRs are simulated with switches in the ON and OFF states inside an ideal simulation environment implemented in the electromagnetic modeling software HFSS where the reflection and transmission coefficients are calculated. Through simulations, each size of SRR is independently optimized and shown to have a broad frequency range where its resonance can be selected from. The two SRRs are subsequently combined in a single structure according to the Sierpiński carpet fractal pattern. This structure is simulated again to obtain a new frequency response with two resonance frequencies near each other. A thin-wire structure is designed and coalesced with the fractal structure which results in a LHM with two transmission bands. Finally, prototypes are fabricated by mechanically etching high-frequency laminates, and tested using standard techniques. Experimental results demonstrate that the fabricated LHM is characterized by two well-defined left-handed transmission bands. Both experimental and theoretical results show a good agreement in predicting the resonances of the complex LHM structure.
Metamaterials, Microresonators (Optoelectronics), Negative refractive index, Magnetic permeability.
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