Abstract: Luneburg lens is a spherical dielectric lens with gradient refractive index. It can concentrate the collimated incident electromagnetic wave on its spherical surface, inversely, it can turn the point wave into plane wave and control the deflection angle of the exit wave. Due to the gradient index and spherically focusing features, the conventional luneburg lens is very difficult to be fabricated and integrated. A novel flattened Luneburg lens with a scanning range of [-90?, 90?] has been realized. Moreover, the lens has a broadband property from 12.4 GHz to 18 GHz. The gradient refractive index structure of the lens was realized by combining a liquid medium approach and the 3D printing technology, which resolved the fabricating problem of the complex structure of the lens. The flexibility of the liquids for a practical implementation endowed this innovative method a wide using perspective to the realization of other microwave devices with high performance.

Key words: 3D printing, gradient index, liquid medium, luneburg lens