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- MakaleAçık Erişim2025Scopus SJRQ1A Hybrid Retrieval Method for an Ω-Class Bianisotropic Metamaterial Using Scattering Parameter Method
Ozturk, Gokhan; Hasar, Ugur Cem; Kaya, Yunus; Korkmaz, Huseyin; Stoyanov, Ivaylo
In this study, a hybrid retrieval method is proposed to retrieve all terms in the electric and magnetic tensors (along with coupling tensors) of Ω -class bianisotropic metamaterial (MM) slabs using scattering (S-) parameters of both normal incidence TE2 mode and oblique incidence TM2 and TE modes. Compared with other extraction methods in the literature, our retrieval method fully characterizes the MM slab (extracts all constitutive parameters) without necessitating any numerical technique (non-iterative) using fewer wave configurations (two modes) and sample configurations (one configuration). Contrary to two sample configurations required in the application of previous retrieval methods in the literature, one sample configuration (with and without its rotation in the transverse plane) significantly decreases the effect of fabrication tolerances on the accuracy of extraction. The proposed extraction method is first validated by a bulk MM slab synthesized by the Lorentz and Drude models. Then, it is applied for extracting the electromagnetic properties of two bianisotropic MM slabs in the form of square split-ring-resonators and Ω -shape using their S-parameters simulated by a full wave simulation program. Finally, its accuracy is examined by comparing simulated S-parameters with those reconstructed by using extracted electromagnetic parameters. It is observed that our proposed method determines the constitutive parameters with a relatively higher accuracy in a relatively short amount of time.
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İncele - 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.
AtıfScopus4WoS4OpenAlex3İncele - MakaleYalnız künye2025Scopus SJRQ1Sensitive Microwave Sensor for Detection and Quantification of Water in Adulterated Honey
Hasar, Hafize; Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Hamdullah; Korkmaz, Huseyin; Yuzgulec, Kadir; Karaaslan, Muharrem; Ebrahimi, Amir; Nayyeri, Vahid; Ramahi, Omar M.
Honey is a rich source of sugar and is one of the indispensable ingredients in infant foods. Thus, it can be subjected to adulteration due to its cost. Measurement techniques such as liquid chromatography and near-infrared spectroscopy, used for detecting any adulteration, are expensive and need to be conducted by highly trained personnel for off-line analysis. Microwave measurements, as a fast, simple, and relatively inexpensive analysis, have recently shown great potential in detecting adulteration within honey samples. Nonetheless, sensor types used in such measurements are conventional. In this study, a reflection-type sensitive microwave sensor terminated by a metal back is proposed for the first time in the literature for the detection and quantification of water percentage ( delta ) level (mass-to-mass basis) within water-adulterated honey samples. When compared with other resonance-based microwave cavity sensors, thanks to its eight strips located at the centers of two closed circular loops, it demonstrates superior frequency selectivity and sensitivity ( S=5.13 %) validated by full-wave 3-D simulations performed by the CST Microwave Studio and equivalent circuit analysis carried out by the Advanced Design System (ADS) software. For example, for ethanol, the proposed sensor gives a frequency shift of more than 1 GHz in the X band. Resonance frequency shift and variation of the reflection coefficient amplitude ( |S11| ) are measured at X band to detect honey samples with up to 8% adulteration level. Three different honey samples (flower honey, highland honey, and thyme honey) were examined to test the performance and applicability of the proposed sensor.
AtıfScopus18WoS14OpenAlex17İncele - MakaleAçık Erişim2024Scopus SJRQ1De-Embedding Technique for Parameter Extraction of Biaxial Bianisotropic Metamaterial Slabs
Hasar, Ugur Cem; Kaya, Yunus; Korkmaz, Huseyin; Iliev, Teodor
Among material classes of isotropic, anisotropic, bi-isotropic, and bianisotropic, the latter class is important because, as different from other classes, the bianisotropic class can describe complex behavior of various materials through tensor expressions between electric and magnetic fields via electric and magnetic flux densities. All electromagnetic parameters (a total of seven) of a general bianisotropic material need to be accurately extracted for understanding its response and characteristic. Extraction methods can be utilized for such a goal. However, the extraction methods in the literature either require a formal calibration procedure or are limited to the extraction of three electromagnetic parameters only. In this study, an attractive self-calibrating waveguide method has been devised for determination of electromagnetic parameters of biaxial biansiotropic metamaterial (MM) slabs. Its first advantage is that it uses a thru connection in addition to the MM-loaded line connection (three different configurations - Case A, Case B, and Case C) and empty-line connection next to the MM-loaded line connection to extract all (seven) constitutive parameters together with the magnetoelectric coupling coefficient. Its second advantage is that it relies on explicit expressions and does not require any calibration process for such an extraction. Simulations and uncalibrated scattering parameter waveguide measurements at X-band (8.2 - 12.4GHz) were performed for a biaxial bianisotropic MM slab made by C-patterned resonators to validate the proposed method. It is observed that extracted electromagnetic parameters by the proposed method satisfy the passivity conditions over the entire frequency band except for a few frequency points or regions (e.g., f = 8.2 GHz). Its reason is expected to be associated with the difficulty in satisfying the continuous medium property at such frequencies. Besides, it is noted that two of the constitutive parameters (ɛ 2 and μ3) illustrate a thickness-resonance behavior revealed by additional measurements of the Case B - MM structure with different lengths (7.675 mm, 9.21 mm, and 10.475 mm). Besides, it is noted that the resonance behavior of the Case C - MM structure changes with a change in periodicity. Specifically, when the periodicity in the x direction of this MM structure changes from approximately 3.26 mm to 2.29 mm, the resonance frequency shifts from nearly 10.43 GHz to 10.30 GHz (a 1.25% variation). Finally, sensitivity, uncertainty, and error analyses were also performed to evaluate and improve its accuracy. It is observed that |3/Λ 1A| | is 14 times greater than | xi 0 / Λ 1A| | at 10.85 GHz where Λ 1A is one of the terms related to measured S-parameters for the Case A - MM structure, and |∗ | denotes the magnitude of the complex number ∗
AtıfScopus1WoS1OpenAlex1İncele