Three-dimensional broadband and broad-angle transformation-optics lens

Area of Science:

• Metamaterials
• Transformation Optics
• Microwave Photonics

Background:

• Luneburg lenses offer superior performance but face manufacturing challenges with gradient-index materials and spherical focal surfaces.
• Two-dimensional (2D) imaging lenses using transformation optics have been developed, overcoming aberrations and offering flattened focal surfaces for wide viewing angles.

Purpose of the Study:

• To design, realize, and measure a three-dimensional (3D) approximate transformation optics lens operating in the microwave frequency band.
• To demonstrate the lens's performance for various polarizations and its potential as a high-gain antenna.

Main Methods:

• Fabrication of the 3D lens using non-resonant metamaterials composed of multilayered dielectric plates with inhomogeneous holes.
• Utilizing transformation optics principles for lens design.
• Conducting simulations and experimental measurements across a broad microwave frequency band (12.4 to 18 GHz).

Main Results:

• The 3D transformation optics lens exhibited excellent performance across different polarizations.
• The lens demonstrated effective operation over a broad frequency band from 12.4 to 18 GHz.
• The lens functioned effectively as a high-gain antenna, capable of radiating or receiving narrow beams at large scanning angles.

Conclusions:

• The realized 3D approximate transformation optics lens shows superior performance in the microwave frequency band.
• The metamaterial-based lens overcomes limitations of conventional Luneburg lenses and offers versatile applications, including high-gain directional antennas.