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- MakaleAçık Erişim2025Scopus SJRQ1Design, Simulation, and Fabrication of High-Performance Metamaterial Absorber for EMI Mitigation and THz NDT/Imaging Applications: A Shape-Preserved GHz-to-THz Transition Approach
Teber, Ahmet
A metamaterial absorber (MMA) designed for the 5G FR2/mmWave bands (24.25–24.45 and 24.75–25.25 GHz) is simulated with CST Studio Suite and fabricated using laser and wet etching techniques. Absorption measurements are performed using horn antennas in conjunction with a vector network analyzer (VNA). The absorber achieves >95.8% absorption under normal incidence for Mode-1, while it exceeds 90% for Mode-2 in the 24.75–25.20 GHz. The simulation results are validated through an electrical equivalent circuit model and experimental data. This absorber presents a promising solution for electromagnetic interference (EMI) reduction and shielding applications. The same structure, scaled from mm to µm without shape alteration, achieved over 90% absorption in the terahertz (THz) region (24–26 THz), particularly in the 24–25.12 THz range. The THz region, known as the “THz gap”, presents challenges due to limited THz sources and detectors. However, technologies such as THz non-destructive testing (NDT) offer potential in biomedical, communication, and defense applications. From this perspective, the high performance and scalability to µm dimensions without changing the shape of the absorber make it suitable for high-frequency EM shielding applications. This dual behavior in the GHz and THz regions offers a versatile advantage due to its varied functionality.
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İncele - MakaleAçık Erişim2024Polarization Insensitive and Thin Metamaterial Absorber Performed in High-Frequency 5G Bands
Arslan Madak, Seher Şeyma; Teber, Ahmet; Topkaya, Ramazan
A variety of fascinating applications, including 5G communication devices, high-speed data transfer, and large-scale Internet of Things (IoT), make life easier with 5G technology. Despite the 5G’s superior features, the percentage of electromagnetic (EM) waves in the environment execute a significant increase, unpleasantly. Broadband metamaterial absorbers are an appealing alternative to gather these unwanted signals. This study aims to numerically investigate a broadband metamaterial absorber (MMA) in the 5G high-frequency spectral range with the metasurface formed with coupled resistors. In addition, the 24.25-27.5GHz frequency range, one of the high-frequency 5G bands used by selected countries such as the European Union and China, was preferred. The minor aim of this study is that the usage of coupled elements as resistors may have the ability to increase the absorption bandwidth and magnitude. Comprehensive simulations were performed using the finite integration technique (FIT) utilized by the CST Microwave Studio program to investigate the absorber performance and other relevant parameters. The unit cell design is created metal-substrate-metal structures as asymmetric, single-layer, and easy to implement. The absorption responses are investigated according to the oblique incidence angle, polarization angle for TE &TM modes. The suggested MMA provided an absorbency response above 87.6% in the frequency range 24.20-27.30GHz under normal incidence. Moreover, to comprehend the physical mechanism on absorption, the top and bottom surfaces of the absorber's electric field and surface current distributions are assessed. The designed MMA resulting in relatively high performance and polarization insensitive is helpful for electromagnetic interference (EMI) shielding of 5G signals in the FR2/mmWave frequency regime.
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İncele - MakaleAçık Erişim2024Scopus SJRQ1FR2/mmWave, N258 and N261 Bands, 5G Frequency-Compatible Ultra-Thin Metamaterial Absorber with Polarization Insensitivity for EMI shielding Applications
Teber, Ahmet
Since adopting 5G technology, a notable rise in the prevalence of electromagnetic (EM) waves in the environment has become a significant concern. To reduce EM interference, broadband metamaterial absorbers offer an alternative solution for protecting devices in defense, communication, and healthcare applications, unlike their narrowband counterparts. This article presents a numerical investigation of an ultra-thin, polarization-insensitive metamaterial absorber (MMA) that uses metasurfaces and provides electromagnetic interference (EMI) reduction, covering the FR2/mmWave licensed N258 and N261 bands with an oblique incidence angle of up to 15 degrees. Comprehensive simulations are performed within the CST Studio Suite S2 2023 to examine the absorber's performance. Under normal incidence, the proposed MMA exhibits a wideband absorbency response exceeding 90% within the frequency range of 24.30–28.12 GHz. Moreover, the physical absorption mechanism is explained with electric and magnetic field distributions, including surface current distributions. Confirmation of the lack of mutual interaction among neighboring unit cells is established through testing with 1 × 2 and 2 × 2 arrays. An equivalent circuit model is also developed to confirm the EM simulation findings. The notable features of the proposed MMA make it an exceptional candidate for EM shielding applications, providing EMI reduction and covering the N258 and N261 bands.
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