Planar Luneburg Lens Based on the High Impedance Surface for Effective Ku-Band Wave Focusing

In this paper, a planar Ku-band Luneburg lens is designed, fabricated, and measured. Based on the high impedance surface, metamaterial units are designed and arranged in an array with gradient equivalent refractive index to achieve good wave focusing effects in the Ku band. The proposed 2-D lens is superior at its compact size and more feasible fabrication process when compared with the conventional 3-D lens. Both theoretical analysis and measurement results have been provided for a systematic study on this lens' performance, and good agreement between them has been achieved. Benefiting from flexible beam steering, the proposed lens has helpful applications in estimating the direction of arrival in the passive direction finding system, improving the directive radiation for an antenna, and simulating increased target's radar cross-section characteristic by adding a reflector.