Thomas Whittaker | Searcharxiv

arXiv2026

Fully 3D-Printed Wideband Metasurface Folded Reflectarray Antenna

This article presents a fully 3D-printed wideband metasurface folded reflectarray antenna (MFRA) operating in the millimeter-wave n257 band. The proposed MFRA integrates a novel polarization-rotating reflective metasurface (RMS), a compact embedded horn feed, and a polarization-selective metasurface polarization grid (MPG), all fabricated using a low-cost in-house 3D-printed method. Unlike conventional PCB-based FRAs constrained to planar unit-cell geometries, the proposed anisotropic meta-element design exploits full three-dimensional dielectric control by tailoring varying unit-cell heights. This volumetric tuning, combined with the spatial distribution of the meta-elements, enables phase compensation exceeding $400^{\circ}$ across the aperture, supporting robust wideband performance. An MFRA prototype is in-house fabricated and experimentally validated. Measured results agree well with simulations, achieving a $-10$ dB impedance bandwidth of 20.7\% (26--32 GHz) and a peak realized gain of 31.1 dBi at 28.2 GHz. The antenna exhibits sidelobe levels below $-20$ dB, cross-polarization below $-30$ dB, and a compact height-to-diameter ratio of 0.20. Stable pencil beams with an average HPBW of $3.7^{\circ}$ are maintained across the operating band. To further validate the robustness of the proposed in-house designed MFRA, a commercially manufactured RMS was also obtained, whose measured performance shows excellent agreement with the in-house 3D-printed version, confirming a cost-effective rapid-prototyping antenna solution. The proposed MFRA is a cost-effective solution for beyond 5G and 6G high-gain point-to-point mmWave wireless applications, such as fixed wireless access, near field communication, and beam focusing.

eess.SP↗

arXiv2024

Shrinking a gradient index lens antenna system with a spaceplate

The miniaturisation of optical systems is an ongoing challenge across the electromagnetic spectrum. While the thickness of optical elements themselves can be reduced using advances in metamaterials, it is the voids between these elements -- which are necessary parts of an optical system -- that occupy most of the volume. Recently, a novel optical element coined a `spaceplate' was proposed, that replaces a region of free space with a thinner optical element that emulates the free-space optical response function -- thus having the potential to substantially shrink the volume of optical systems. While there have been a few proof-of-principle demonstrations of spaceplates, they have not yet been deployed in a real-world optical system. In this work, we use a bespoke-designed spaceplate to reduce the length of a gradient index (GRIN) lens microwave antenna. Our antenna is designed to operate at 23.5 GHz, and the incorporation of a nonlocal metamaterial spaceplate enables the distance between the antenna feed and the GRIN lens to be reduced by almost a factor of two. We find the radiation patterns from a conventional and space-squeezed antenna are very similar, with a very low cross-polarisation, and only a minor increase in the side-lobe levels when introducing the spaceplate. Our work represents a first example of a spaceplate integrated into a functional optical system, highlighting the potential for this concept to reduce the physical size of optical systems in real-world applications.

physics.app-ph↗