Abstract
In this letter, we present the experimental validation of a $K_{a}$ -band Luneburg lens antenna based on a novel cost-effective metasurface. The metasurface is composed of a parallel plate waveguide (PPW) loaded with quasi-periodic inclusions in both conductors. The inclusions are square holes printed on a substrate, with vias placed around the holes. The vias connect the printed layer of the substrate to the ground. This configuration is named substrate-integrated hole (SIH). It is demonstrated that the SIH metasurface can obtain a higher effective refractive index, compared to the conventional holey metasurface. To further increase the effective refractive index, the SIHs in the two conductors of the PPW are glide-symmetrically arranged. The refractive index distribution of the Luneburg lens is realized by locally tuning the dimensions of the SIHs. The lens is fed with 11 waveguide feeds with an angular separation of 10 $^{\circ }$ . Thus, the antenna can steer its radiation in a 100° angular range. A flare is integrated with the PPW to match the antenna to the free-space impedance. Since the wave propagates mainly in the PPW air gap, the dielectric losses are low. The measured radiation efficiency of the antenna is roughly 80%.
Highlights
T HE requirements for high data rate and short delays in the new wireless networks can be satisfied using a high operation frequency [1]
We present the experimental validation of an efficient Ka-band Luneburg lens antenna suitable for mass production
The antenna is based on the substrate-integrated hole (SIH) metasurface, which consists of an array of cavities loaded into the two conductors of a parallel plate waveguide (PPW)
Summary
T HE requirements for high data rate and short delays in the new wireless networks can be satisfied using a high operation frequency [1]. The frequencies around 28 GHz have received significant attention for the future generations of the mobile communication networks [2] At these frequencies, the losses in free-space propagation and materials are high, which makes the design of efficient antennas challenging. In metasurface Luneburg lenses, the gradual refractive index is realized with a quasi-periodic structure. Metallic metasurface Luneburg lens antennas were presented in [16]–[19] and a radiation efficiency of 88% was demonstrated [16]. These metasurfaces must be milled, which results in a high cost.
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