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Three-Dimensional Super Lens Composed of Fractal Left-Handed Materials




Inspired by the fractal concept, a miniaturized and fully printed planar, left-handed (LH) material with C band (from 4.89 to 5.55 gigahertz) negative permittivity and permeability is proposed, using the transmission-line (TL) approach. By incorporating four interdigital capacitors in the Sierpinski fractal curves of the second iteration order, the resulting LH-TL material features large inductance and capacitance values in the equivalent circuit model, and thus facilitates an electrically small dimension and a broadband negative magnetic response. Based on the planar LH-TL materials and sophisticated theory, a three-dimensional (3D) free-space LH-TL super lens is designed and fabricated using multiple structures. Both numerical and experimental results illustrate that the 3D super lens exhibits excellent impedance matching to free space and significantly improves the imaging resolution. It is shown that the resolution reaches 0.39 λ0 at 5.35 gigahertz, in which the LH-TL material possesses μ ≈ –μ0 and ε ≈ –ε0 (μ0 and ε0 are free-space permeability and permittivity).