Laser-Drilled All-Dielectric Huygens’ Transmit-Arrays as 120 GHz Band Beamformers

Mohamed K Emara,Takashi Tomura,Shulabh Gupta,Jiro Hirokawa,Sonya K Stuhec-Leonard

doi:10.1109/access.2020.3018297

Mohamed K Emara, Takashi Tomura + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.3018297

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Abstract

An all-dielectric Huygens’ transmit-array is proposed and experimentally demonstrated in the 120-GHz-band. The proposed transmit-array is fabricated using a high-precision laser-drilling process providing high fabrication precision and accuracy. A non-uniform Huygens’ surface is next placed on top of a planar high gain slot-array antenna for far-field beamforming. Full-wave simulations are first used to demonstrate the beamforming capability by generating difference-pattern beams as an example. A uniform transmit-array was then fabricated and characterized to investigate the effect of the transmit-array on the antenna performance, along with showing very low fabrication tolerances and minimal dimensional variation due to the laser drilling process. Next, a phase-gradient transmit-array for beam-tilting is experimentally demonstrated as a practical example of beamforming. The proposed all-dielectric structure is the first Huygens’ structure to be demonstrated at these frequency bands, and represents an attractive alternative to conventional metallic Huygens’ metasurfaces based on standard printed circuit board (PCB) solutions.

Highlights

Electromagnetic metasurfaces are 2-D structures that consist of arrays of sub-wavelength resonators [1]
Metasurfaces, and in particular Huygens’ metasurfaces, can be broadly classified into two categories based on their design: metallic metasurfaces and all-dielectric metasurfaces
Metallic metasurfaces are composed of unit cells that consist of metallic patterns, most commonly implemented on a dielectric substrate using standard printed circuit board (PCB) processes, at microwaves [19]–[27]

Summary

INTRODUCTION

Electromagnetic metasurfaces are 2-D structures that consist of arrays of sub-wavelength resonators [1]. Some efforts have been made to realize photonics inspired all-dielectric metasurface structures at microwaves [2], [28], [29], [31] and mm-wave frequencies [47], as an alternative to metallic resonator-based metasurfaces Such structures are based on mechanically drilling typical substrate materials, as opposed to standard PCB processes, to form dielectric resonators connected using bridges. With the upcoming sixth generation (6G) communication networks [49] being expected to see a high demand for antenna beamforming techniques above 100 GHz, there is an interest in devising novel ways to enable general wave transformations It can either be in the form of novel antenna structures or achieving beam shaping using external phase plates realized using metasurfaces, for instance, where Huygens’ metasurface can be used for engineering the near-field distribution of directive, high gain antennas [50].

ALL-DIELECTRIC VS METALLIC CELL

PHASE-GRADIENT TRANSMIT-ARRAY

CONCLUSION

Design Average measured Deviation