Metamaterial Lens Design for Electronically Steered Arrays

A metamaterial lens (metalens) is engineered to improve the scanning performance of a dipole array. When placed within the lens, each dipole has an embedded element radiation pattern with a relatively flat top and a much narrower beamwidth than without the lens. This is ideal for an electronically steered array (ESA) with large element spacing, since the narrow beamwidth of the embedded element pattern suppresses grating lobes. When only the permittivity of the lens is optimized, the lens creates a flat-top pattern in only one plane; however, when both the permittivity and permeability are optimized a flat-top embedded pattern in both planes is achievable. Simulated results indicate that for a small square array, the lens enables a directivity increase of 9 dB. Furthermore, grating lobe levels are significantly reduced without increasing scan loss.