Ultra-Wideband Flat Metamaterial GRIN Lenses Assisted with Additive Manufacturing Technique

This article presents the designs of ultrawideband microwave flat gradient index (GRIN) lenses, which realizes over a 108% fractional bandwidth (12–40 GHz). The frequency-independent ray optics method is employed to determine the radially varying permittivity profile of the lenses. The challenge of realizing such a radially varying profile and the limitations in dielectric material choices are ove...