Efficient synthesis of high-performance millimeter-wave metasurfaces

Project Information

MILLISURF

Grant agreement ID: 101146306

DOI

10.3030/101146306

EC signature date 22 March 2024

Start date 1 September 2024

End date 28 February 2027

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 230 586,48

Coordinated by

ARISTOTELIO PANEPISTIMIO THESSALONIKIS
Greece

Periodic Reporting for period 1 - MILLISURF (Efficient synthesis of high-performance millimeter-wave metasurfaces)

Reporting period: 2024-09-01 to 2026-02-28

Summary of the context and overall objectives of the project

As 5G wireless networks roll out and 6G networks are being developed, there is a growing need for higher speeds and greater capacity. To meet this demand, communication systems are shifting to higher frequencies such as millimetre-waves (mm-waves). Fabricating components for these frequencies is challenging, as the smaller sizes require new materials and techniques. Metasurfaces, which can control electromagnetic waves, present a cost-effective alternative to traditional devices. However, the analysis and synthesis of metasurfaces becomes computationally demanding as their complexity increases. MILLISURF aims at developing semi-analytical formulations that will enable fast and efficient synthesis of high-performance optimized metasurfaces, suitable for mm-Wave communications. It will also harness advanced fabrication methods to facilitate the realization of optimized metasurface components. The synthesized metasurfaces will also be easy-to-fabricate, low-cost and lightweight, suitable for mm-Wave communications. The MILLISURF project consists of the following major research objectives: (i) Introduction of novel robust semi-analytical formulations for accurate and fast approximation of large-scale metasurface response, (ii) Design of novel, easy-to-fabricate, low-cost, and lightweight mmWave components, such as absorbers, filters, polarization-converters, and gratings, (iii) Development of a fast and efficient optimization framework based on semi-analytical methods, (iv) Fabrication and experimental characterization of the optimized mm-Wave components. By combining computational efficiency, optimized performance and highly accurate fabrication methods, optimized devices are realized within MILLISURF, which enhance the reliability and robustness of 5G and future 6G communication systems. The meticulously and efficiently designed mm-Wave components will be readily integratable with existing mm-Wave solutions.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In the context of MILLISURF, a semi-analytical Method-of-Lines (MoL) formulation was developed for the fast and computationally efficient analysis and design of metal-based periodic mmWave metasurfaces. The MoL offers a considerably faster alternative to the full-wave finite element method, as the electromagnetic equations are solved analytically along the direction perpendicular to the MS layers and numerically on the MS plane; hence, the required degrees of freedom (DoFs) are substantially decreased. The MoL formulation was used to analyze ring resonator filter designs that achieve band-stop regions in the Ka-band, providing a fast and accurate response of such metasurfaces. To render the MoL extendable to metasurfaces of even larger cross-sections, eigenmode-free MoL formulations were also developed, which use analytical expressions to calculate the system matrix. Reconfigurable metasurfaces were analyzed by the eigenmode-free MoL to demonstrate the significant speed-up against full-wave methods, especially as the number of states increases. Additionally, a coupled-mode-theory formulation was developed to guide the synthesis of mm-wave metamaterial-inspired substrate integrated waveguides (SIW), based on uniplanar complementary split-ring resonator (CSRR) metasurfaces. The uniplanar CSRR SIW components offer simpler fabrication and similar performance to the conventional SIW, as confirmed by both simulations and measurements. Furthermore, the BINACONN and BINACINN3D methodologies were developed to transform complex-shaped optimized metamaterial devices into manufacturable ones, preserving performance. By employing the developed methodologies, we designed a wide-angle free-form 3D-printable metagrating that achieves higher efficiency than metagratings of simpler geometric shapes and is manufacturable by stereolithography 3D-printing. Multi-layer metamaterial absorbers, based on MXene patch resonators and spatially variable 3D-printable dielectric substrates, were also designed using BINACONN3D, to enhance the absorption bandwidth of MMAs with constant dielectric substrates. Simulations and measurements confirm the enhanced absorption bandwidth of the designed MMAs.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The developed semi-analytical MoL formulation allows the analysis of periodic metal-based metasurfaces considerably faster than the full-wave finite element method. This speed-up will be particularly useful for the synthesis of metasurfaces, where parametric analysis or optimization requires numerous simulations. The MoL simulations have lower computational requirements than the finite element method and therefore need fewer resources and entail lower costs. The eigenmode-free MoL is even more advantageous, as it calculates the S-parameter matrix by analytical closed-form expressions with complexity O(n2), which is significantly lower than the O(n3) required for a dense eigensolver used in existing MoL formulations. A key need to ensure further uptake is further research, which will combine the developed MoL with optimization frameworks. This step will be part of MILLISURF’s return phase. The developed methodologies, BINACONN and BINACONN3D, transform complex-shaped optimized metamaterial devices into manufacturable ones, preserving the performance of the optimized non-manufacturable devices. They are effectively employed to synthesize free-form 3D-printable optimized devices that surpass the performance of state-of-the-art devices with simpler geometric features. Combining high-precision 3D-printing with inverse design techniques paves the way to realizing high-performance components that can be used in future wireless communications. The synthesized mmWave uniplanar CSRR SIW components and antennas offer similar performance to the conventional SIW, while also being easier to fabricate. Such CSRR SIW components can be employed in 5G/ 6G applications, offering a lower-cost solution.