Near-Zero-Index Metamaterial Lens Combined With AMC Metasurface for High-Directivity Low-Profile Antennas

A high-gain reduced-profile antenna is designed by combining the effects of a near-zero-index volumetric metamaterial lens and an artificial magnetic conducting (AMC) ground plane. The AMC/metalens antenna design presented here has 20% reduced height over an equivalent metalens antenna with conventional metallic ground plane at the cost of reduced peak directivity and pattern bandwidth. Both the metamaterial unit cells and the mushroom-type AMC structure are designed independently and retuned in the presence of the other for optimal performance. The lens collimates the electromagnetic radiation of a dipole feed by refraction as well as via a Fabry-Perot cavity effect, with resulting gain and patterns that are better than either mechanism can achieve individually. Full wave simulations of the entire metamaterial and AMC structure with a feed dipole agree well with measurements of the fabricated design.