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

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 transmitarray 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 beamtilting 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.

A Low-Profile Transmissive Metasurface for Transformation of Plane Wave to Contour Beam Pattern Using 4-Arm Spiral Element

“…However, APM is a local search algorithm, so it may converge to undesired local minima due to large number of phase variables or complicated mask for the desired contour beam pattern [17], [25]. Similar configurations for slot array feed and transmissive metasurface are also used for focused beam transformation [26], [27] and quad-beam pattern synthesis [3]. However, focused beam transformation is achieved through simple phase-gradient distribution, while quad-beam pattern synthesis problem is quad-symmetric, so it is also much simpler problem with 1/4 phase variables as compared to asymmetric and complicated contour beam pattern synthesis problem.…”

Part 1: Spatially Dispersive Metasurfaces: Zero Thickness Surface Susceptibilities & Extended GSTCs

“…3(a) [17]. They have also been proposed at millimeter-wave frequencies in both all-dielectric [32]- [34] and standard printed circuit board implementations [18]. One common feature among all these structures is their relatively large unit cell sizes which can approach free-space wavelength, making them weakly sub-wavelength.…”

Bipartite dielectric Huygens’ metasurface for anomalous refraction

“…Such meta-devices are also of the utmost importance for microwave and millimeter-wave applications, such as beamforming, polarization control, gain enhancement, among many others. Nonetheless, the capabilities of dielectric metasurfaces, including DHMS, are not much explored in the microwave and mm-wave regimes, and only a handful of designs have been reported [38,39,[46][47][48][49][50]. The implementation of wave-deflection meta-devices in [17,18,36,38,40,[48][49][50] employs the phase gradient approach based on the generalized Snell's laws [51].…”

“…Nonetheless, the capabilities of dielectric metasurfaces, including DHMS, are not much explored in the microwave and mm-wave regimes, and only a handful of designs have been reported [38,39,[46][47][48][49][50]. The implementation of wave-deflection meta-devices in [17,18,36,38,40,[48][49][50] employs the phase gradient approach based on the generalized Snell's laws [51]. Such phase-gradient meta-devices suffer from low efficiencies, especially at the extreme steering angle [52,53].…”

“…It efficiently (87% refraction efficiency) redirects an incoming linearly polarized wave at θ i = 15°towards θ t = − 44.5°, with nearzero reflections. Thanks to the coarse discretization, we arrive at a design that is a combination of high angular deflection and high power efficiency unmatched by most dielectric metasurfaces [17,18,36,40,41,[48][49][50]. We also present a systematic design approach and analysis that allows the metasurface to be tailored for different parts of the electromagnetic spectrum.…”