Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2023Scopus SJRQ1Temporal Reflection Response of Plane Waves Within an N-Layer Structure Involving Bianisotropy
Hasar, Ugur C.; Ozturk, Gokhan; Kaya, Yunus; Barroso, Joaquim Jose; Ertugrul, Mehmet; Ramahi, Omar M.; Alfaqawi, Mona S. S.
The temporal reflection response of an N-layer composite structure involving bianisotropic behavior is examined for the first time in the literature. Toward this goal, the wave matrix (WM) method, which is fundamental, relatively easier to apply, and compact and iterative suitable for analysis of multilayer structures, is first extended to the analysis of an interface separating two different media involving bianisotropy. Next, the reflection response of the whole structure is derived in terms of series form to better analyze its temporal behavior. Then, frequency-domain and time-domain responses of the whole structure are expressed using a special reflection coefficient (the reduced reflection coefficient) by way of the concept of subregions. A numerical analysis is performed to demonstrate the applicability of our formalism for two different polarization types (perpendicular and parallel).
AtıfScopus3WoS3OpenAlex3
İncele - MakaleYalnız künye2023Scopus SJRQ1Extraction Method for Unique Determination of Complex Permittivity From Graphical Analysis of Natural Frequencies
Hasar, Ugur C.; Ozturk, Gokhan; Kaya, Yunus; Alfaqawi, Mona S. S.; Barroso, Joaquim Jose; Ertugrul, Mehmet; Ramahi, Omar M.
A time-domain free-space extraction procedure is proposed to uniquely determine the relative complex permittivity epsilon(r)(omega) based on two sets of natural frequencies of the metal- and air-backed dielectric samples. A graphical analysis is applied for evaluating whether unique epsilon(r)(omega) can be extracted using such natural frequencies. The method is numerically validated using two dielectric samples with different epsilon(omega) for the ideal case (no noise) and under the influence of noise with different signal-to-noise ratios (SNRs).
AtıfScopus1OpenAlex1İncele - MakaleAçık Erişim2022Scopus SJRQ1Broadband Soil Permittivity Measurements Using a Novel De-Embedding Line-Line Method
Hasar, Hafize; Hasar, Ugur C.; Kaya, Yunus; Oztas, Taskin; Canbolat, Mustafa Y.; Aslan, Nevzat; Ertugrul, Mehmet; Ramahi, Omar M.
A new de-embedding line-line method has been proposed for accurate complex relative permittivity ( ε ᵣ ) determination of soil samples loaded into an EIA 1-5/8' coaxial transmission line measurement system. The method has three main features. First, it bypasses the requirement of calibration of this system by using only two identical coaxial lines with different lengths. Second, it does not need any numerical technique for ε ᵣ determination. Third, it does not require knowledge of electromagnetic properties and thickness information of the bead used for supporting soil samples. The method is next validated by simulations performed using a full 3-D electromagnetic simulation program (CST Microwave Studio) and by ε ᵣ measurement of a polyethylene (PE) material. Finally, ε ᵣ values of three air-dried and water-saturated soil samples having 90% or more sand content with different electrical conductivities (ECs) and gathered from different areas of the city Gaziantep in Turkey, were measured.
AtıfScopus18WoS16OpenAlex16İncele - MakaleAçık Erişim2022Scopus SJRQ1Calibration-Free Time-Domain Free-Space Permittivity Extraction Technique
Hasar, Ugur C.; Ozturk, Gokhan; Kaya, Yunus; Ertugrul, Mehmet
A time-domain free-space technique has been proposed to extract relative permittivity ( _r ) and effective conductivity ( σ _e ) of low-loss dielectric samples using their metal- and air-backed calibration-free reflected powers. Numerical computations and 3-D electromagnetic simulations were performed to validate the method. A sensitivity analysis was carried out to examine its accuracy. Calibration-free time-domain free-space measurements over 1-12 GHz were conducted by VNA to extract _r and σ _e of polyethylene and polypropylene low-loss samples.
AtıfScopus29WoS28OpenAlex29İncele - MakaleAçık Erişim2022Scopus SJRQ1Broadband, Stable, and Noniterative Dielectric Constant Measurement of Low-Loss Dielectric Slabs Using a Frequency-Domain Free-Space Method
Hasar, Ugur C.; Kaya, Yunus; Ozturk, Gokhan; Ertugrul, Mehmet; Korasli, Celal
A broadband, stable, and noniterative free-space method is proposed for dielectric constant ϵr′ determination of low-loss dielectric slabs from reflection-only measurements through simple calibration standards (reflect and air). It is applicable for dispersive samples and does not require thickness information. Simulations of nondisperive and dispersive samples are performed to validate our method. Dielectric constant measurements of polyethylene and polyoxymethylene samples (9-11 GHz) are carried out to examine the accuracy of our method.
AtıfScopus41WoS37OpenAlex35İncele - MakaleAçık Erişim2022Scopus SJRQ3IoT-TDMA: A performance evaluation of TDMA scheme for wireless sensor networks with Internet of Things
Kosunalp, Selahattin; Kaya, Yunus
This article focuses on the design and implementation of an improved version of TDMA scheme for wireless sensor networks (WSNs) exploiting the Internet of Things (IoT) phenomena. The main motivation behind this work is to create an environment for WSNs to benefit from IoT opportunities. An extensive review of the state-of-the-art medium access control (MAC) approaches proposed for IoT is carried out underlying their basic principles and features. An adaptation of TDMA strategy, called IoT-TDMA, is proposed to enhance the channel performances particularly throughput and latency. To test the performance of IoT-TDMA practically, a low-cost node hardware with the capability of Internet connection is essentially designed. IoT-TDMA has been implemented on real-world highly scalable single-hop and multi-hop topologies. Performance results indicate significant improvements in terms of channel throughput and end-to-end delay in comparison to a recently proposed efficient MAC scheme.
AtıfScopus17OpenAlex18İncele - MakaleAçık Erişim2022Scopus SJRQ1Improved Method for Permittivity Determination of Dielectric Samples by Free-Space Measurements
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Hamdullah; Izginli, Mucahit; Ertugrul, Mehmet; Barroso, Joaquim Jose; Ramahi, Omar M.
A new deembedding technique is proposed for relative complex permittivity epsilon(r) determination of dielectric materials using gated free-space measurements. Its three main features are 1) it does not require any formal calibration procedure (calibration-free); 2) it is position-insensitive; and 3) it extracts ripple-free epsilon(r) due to gating process. The objective function derived to determine epsilon(r) by the proposed method is validated by free-space measurements of three dielectric samples (polypropylene, polyethylene, and polyoxymethylene). Besides, the accuracy of our method is compared with the accuracy of other calibrationfree and calibration-dependent methods in the literature.
AtıfScopus49WoS36OpenAlex44İncele - MakaleAçık Erişim2022Scopus SJRQ1Determination of Propagation Constants and Wave Impedance of Non-Reciprocal Networks From Position-Insensitive Waveguide Measurements
Hasar, Ugur C.; Kaya, Yunus; Izginli, Mucahit; Ozturk, Hamdullah; Barroso, Joaquim J.; Ramahi, Omar M.; Ertugrul, Mehmet
A microwave method is proposed to determine the forward and backward propagation constants (gamma ⁺ and gamma ⁻) and the wave impedance ( z_w ) of reciprocal and non-reciprocal microwave networks whose positions are not known within their measurement cells (position-insensitive). The proposed method relies purely on analytical expressions and can also evaluate the reference plane transformation distances. Scattering parameter measurements at the X-band (8.2-12.4 GHz) of a reciprocal network (a waveguide straight) and a non-reciprocal network (a microwave phase shifter) arbitrarily positioned into their measurement cells were conducted to retrieve gamma ⁺, gamma ⁻, and z_w for validation of our method and testing its position-insensitive property. The importance of the method becomes apparent when compared to conventional methods whose accuracy is based on precise determination of the reference planes.
AtıfScopus9WoS9OpenAlex9İncele - MakaleYalnız künye2022Scopus SJRQ1Complex Permittivity and Thickness Evaluation of Low-Loss Dielectrics From Uncalibrated Free-Space Time-Domain Measurements
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Hamdullah; Izginli, Mucahit; Barroso, Joaquim Jose; Ramahi, Omar M.; Ertugrul, Mehmet
A free-space time-domain method is proposed to retrieve dielectric constant (epsilon r), conductivity (sigma e), and thickness (d) of metal-backed low-loss dielectric samples using calibration-independent reflected power peak measurements. Its algorithm is validated by numerical calculations and simulations (CST Microwave Studio) using a sine-modulated Gaussian window. A sensitivity analysis is followed to examine its performance considering the dependencies of reflected power peaks with respect to epsilon r and sigma e. Free-space time-domain measurements have been implemented after transforming frequency-domain measurements into time-domain ones to extract epsilon r, sigma e, and d of polypropylene, polyethylene, and polyoxymethylene samples.
AtıfScopus48WoS42OpenAlex43İncele - MakaleYalnız künye2022Scopus SJRQ1Feasible Extraction Method for Electromagnetic Properties of Multilayer Metamaterials With Short-Circuit Termination
Hasar, Ugur Cem; Ozturk, Gokhan; Kaya, Yunus; Bute, Musa; Karaaslan, Muharrem; Barroso, Joaquim J.; Ramahi, Omar M.; Ertugrul, Mehmet
An extraction technique is proposed for electromagnetic characterization of metal-backed multilayer metamaterial (MM) structures demonstrating reflection-asymmetric property. It uses recursive scattering parameters for direct and reversed configurations of a multilayer structure. The algorithm was validated by comparing the extracted electromagnetic properties of multilayer structures composed of different MM unit cells with those determined by one-layer-only S-parameter methods. Two-layer and three-layer multilayer structures composed of MM slabs with C-shaped and Omega-shaped rings and an FR4 material were fabricated and measured for experimental validation. A sensitivity analysis was also conducted to quantitatively evaluate the performance of our method against a small air gap between the multilayer structures and the short-circuit termination and between adjacent MM slabs within these structures. Strong agreement was observed between the resulted obtained using our method and measurements.
AtıfScopus10WoS10OpenAlex10İncele - MakaleAçık Erişim2021Feasible Waveguide Method for Obtaining ElectromagneticProperties of Biaxial Bianisotropic Materials with Strong Magneto Electric Coupling
Kaya, Yunus
In this study, an easy-to-apply waveguide method is proposed for material characterization of biaxial bianisotropic samples withstrong magneto-electric coupling. Its underlying expressions are derived considering scattering (S-) parameters of the sample at onefixed orientation in two waveguides at their dominant modes with different cross sections. The method is validated by synthesized andretrieved electromagnetic properties of a sample when there is no/some noise.
- MakaleAçık Erişim2021Scopus SJRQ1Measurement of Propagation Characteristics of Nonreciprocal Networks/Lines Using a Line-Line Method
Hasar, Ugur C.; Kaya, Yunus; Ertugrul, Mehmet
In this article have proposed a new calibration-free line-line method for propagation constant (gamma) determination of homogeneous nonreciprocal networks or lines with symmetric reflection property. To achieve our goal, wave-cascading matrices for impedance, amplitude, and phase changes for a line step from a homogeneous reciprocal network or line to a homogeneous nonreciprocal network or line (and vice versa). Two different approaches based on the proposed line-line method are proposed for unique extraction of gamma in forward and backward directions. Measurements of gamma for two reciprocal lines (waveguide straights at X-band and Ku-band with different lengths) and a nonreciprocal line (microwave phase shifter) were first carried out and then compared with measured gamma of these lines by different methods to validate our method and monitor its accuracy.
AtıfWoS4OpenAlex5İncele - MakaleAçık Erişim2021Scopus SJRQ1Simple and accurate electromagnetic characterization of omega-class bianisotropic metamaterials using the state transition matrix method
Hasar, Ugur C.; Ozturk, Gokhan; Kaya, Yunus; Barroso, Joaquim J.; Ertugrul, Mehmet
We propose a simple and accurate microwave extraction procedure for full electromagnetic characterization of \Omega -class bianisotropic metamaterial (MM) slabs from normal incidence scattering (S-) parameters using TE1, TE2, and TE3 modes. Its closed-form nature (no need for any numerical analysis and optimization toolbox) and less requirement (a total of seven S-parameters) demonstrate the advantage of our method over other methods in the literature. Our approach was validated and its accuracy was verified by S-parameters, through a full electromagnetic simulation program - CST Microwave Studio, of an edge-coupled \Omega -class split-ring-resonator MM slab.
AtıfScopus15WoS13OpenAlex14İncele - MakaleAçık Erişim2021Scopus SJRQ1Parameter Retrieval of Samples on a Substrate from Reflection-Only Waveguide Measurements
Hasar, Ugur Cem; Ozturk, Hamdullah; Kaya, Yunus; Izginli, Mucahit; Ertugrul, Mehmet
A microwave method has been proposed for constitutive parameters' extraction of samples on a known substrate. The advantage of this method is that it relies on noniterative reflection-only (air-and metal-backed) scattering (S-) parameters so that it is a good candidate for the characterization of samples when only one-port measurements are available. It is validated by the X-band (8.2-12.4 GHz) waveguide S-parameter measurements. A sensitivity analysis is followed to evaluate and improve the performance of our method.
AtıfScopus5WoS5OpenAlex3İncele - MakaleAçık Erişim2021Scopus SJRQ1Prediction of water-adulteration within honey by air-line de-embedding waveguide measurements
Hasar, Hafize; Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Hamdullah; Izginli, Mucahit; Ozbek, Ibrahim Yucel; Oztas, Taskin; Canbolat, Mustafa Yildirim; Ertugrul, Mehmet
An efficient de-embedding air-line microwave method has been proposed for accurate relative complex permittivity, εr=εr′−iεr′′, measurement of water-adulteration level within honey. It could be effectively applied to eliminate the errors arising from usage of imperfect calibration standards because it bypasses the requirement of these standards. Its accuracy is improved by utilizing the unitary and similarity properties of a passive two-port network, and then is compared with the accuracy of a calibration-dependent method present in the literature by using normalized root-mean-square-error (N-RMSE) values of εr′ and εr′′ of distilled water, in reference to the Debye value. From this comparison, it is observed that N-RMSE values calculated for εr′ (and εr′′) by using this calibration-dependent method and the (improved) proposed method are, respectively, around 0.1955 (0.1002) and 0.1962 (1.1067), indicating a good agreement between them. After validation the proposed de-embedding method using distilled water measurements, tested pure honey was adulterated with distilled water by different percentage values δ ranging from 1% to 10% in 1% increments. It is observed that the maximum distance between extracted εr′ (or εr′′) values of adulterated honey by the applied calibration-dependent method and the proposed method is less than 2%. Afterward, an empirical formula was devised to fit εr′ and εr′′ values from measured εr of water-adulterated honey with various δ levels. It is noted that extracted εr′ is much more better fitted than extracted εr′′, especially for δ≤4. Next, an optimization process is followed to evaluate the frequency for optimum prediction of adulteration levels using the empirical formula based on εr′ or εr′′. It is noticed that optimized δ values using the empirical formula based on εr′ (with an average prediction error of around 0.071 at 4.5 GHz) are superior to optimized δ values using the empirical formula based on εr′′ (with an average prediction error of around 0.085 at 4.2 GHz) for prediction of previously known δ values. Sensitivity and uncertainty analyses were performed to assess and improve the accuracy of the proposed method.
AtıfScopus24WoS23OpenAlex24İncele - MakaleAçık Erişim2021Scopus SJRQ1Effect of sample deformation in longitudinal axis on material parameter extraction by waveguides
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Gokhan; Ertugrul, Mehmet
An analysis was performed for examining the consequences of sample deformation in longitudinal axis in the sample-loaded non-resonant waveguide techniques. Vertical and horizontal deformations were first simulated to understand the change in field distributions and corresponding scattering parameters. Then, effects of sample length, dielectric constant, and loss factor for these deformations on extracted electromagnetic properties were analyzed using simulated results. Finally, S-parameter measurements were carried out to understand the effect of vertical deformation on permittivity results and to examine any improper sample preparation by hand-made and machine-made samples by applying a statistical model based on mean, standard deviation, coefficient of variation, and confidence interval. It was noted that extracted dielectric constants of each tested dielectric sample (polyethylene, polypropylene, polyvinyl-chloride) were within the confidence interval range of 90% while their retrieved loss factors were within the confidence interval range of 90%, 95%, or 98%.
AtıfScopus3WoS3OpenAlex3İncele - MakaleYalnız künye2021Scopus SJRQ1Graphical Method for Examining Complex Natural Frequencies of Dispersive Materials
Hasar, Ugur C.; Ozturk, Gokhan; Barroso, Joaquim J.; Gurbuz, Tolga U.; Kaya, Yunus; Ertugrul, Mehmet
A graphical method is extended to and applied for visual inspection of solution patterns (region of complex natural frequencies sₙ) in the complexs-plane for dispersive materials characterized by the Debye and Lorentz models. These patterns are in the form of exponential decay and C-shaped profiles for the Debye and Lorentz models, respectively. Their forms are observed to be affected (e.g., moving left/right) in different manners with a variation of dispersion parameters. This method, thanks to its visual inspection capability, can help in analyzing/synthesizing filters and frequency-selective surfaces.
AtıfScopus6WoS6OpenAlex7İncele - MakaleAçık Erişim2021Scopus SJRQ1New formalism for characterization of simple non-reciprocal networks free from singularity-point problem
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Gokhan; Ozturk, Hamdullah; Izginli, Mucahit; Ertugrul, Mehmet
A method has been proposed for accurate characterization of non-reciprocal networks without enforcing the passivity principle. Thanks to the introduced different even and odd coefficients, our method has no singularity-point problem as compared with the conventional method. The proposed method is validated by scattering parameter measurements of a ferrite-loaded waveguide shifter. In addition, it is demonstrated by measurements that our method, as compared with the conventional one, is more resistant to random noise due to post-calibration effects.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2021Scopus SJRQ1Coupling analysis between resonating metamaterial slabs using scattering parameters
Hasar, Ugur Cem; Kaya, Yunus; Izginli, Mucahit; Ozturk, Hamdullah; Ertugrul, Mehmet; Ramahi, Omar M.
Metamaterial (MM) slabs in close proximity can couple with one another. This coupling can modify the electromagnetic response of the overall MM structure involving individual MM resonators. The signal flow graph technique along with the ABCD parameters are applied to quantitatively and qualitatively examine this coupling from simulated/measured scattering parameters of cascade connection of closely or largely separated MM slabs. S-parameter measurements of a MM slab constructed by split-ring-resonators were carried out at X-band (8.2-12.4 GHz) to validate our theoretical analysis.
AtıfScopus2WoS2OpenAlex2İncele - MakaleAçık Erişim2020Scopus SJRQ1Propagation constant measurements of reflection-asymmetric and nonreciprocal microwave networks from S-parameters without using a reflective standard
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Gokhan; Ertugrul, Mehmet
We propose a simple method for determination of forward and backward propagation constants of nonreciprocal uniform networks or lines with asymmetric reflections. The wave cascading matrix presentation is used to diagonalize and decompose the line in terms of impedance and amplitude/phase transitions. The proposed method uses scattering parameters of the line/network connection and the thru connection, thus eliminating errors arising from fabrication tolerance and thickness of the second line. Besides, compared with conventional methods which necessitate calibration techniques such as the thru-reflect-line, our method has the advantage that it determines propagation constants without resorting the measurement of any reciprocal reflective standard. Propagation constant measurements of a reciprocal network (different-length X-band waveguide straights) and a nonreciprocal network (microwave phase shifter) were first carried out and then compared with those measured by different methods to validate and monitor the accuracy of our method.
AtıfScopus13WoS12OpenAlex11İncele
