A 3-D Printed Ultra-Wideband Achromatic Metalens Antenna

Lens antennas, which can transform the incident spherical wavefronts to planar above the radiating aperture, have attracted increasing attention due to their simple structure and high gain performance. Nevertheless, conventional lens antennas face with the problem of dispersion effects, which hinders their applications in large bandwidth and multi-channel communications. In this article, we propose a millimeter-wave achromatic metalens antenna using three-dimensional (3D) printing technology to reduce the dispersion effect and enlarge its bandwidth. The proposed ultra-wideband achromatic metalens antenna consists of a convex-liked metalens (VLM) and a concave-liked metalens (CLM) integrated as a metalens group. The VLM is designed on the basis of dielectric posts with different heights. The calculated transmission phase (from 0 to $2\pi$ ) of VLM can be realized by changing the height of dielectric posts. The CLM consists of discrete variable-width dielectric posts with two different heights to achieve desired transmission phase. Measured results demonstrate that the maximum realized gain is 23.27 dBi, and the return loss is smaller than −15 dB within the whole operating bandwidth. More importantly, a broad 3-dB gain bandwidth of more than 68.4% has been achieved to cover nearly the entire V and W bands, ranging from 50 to 102 GHz.