Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Conference Object Citation - Scopus: 1A Compact Dual-Band Gcpw-Fed Antenna for Wlan, Wimax and Bluetooth Applications(IEEE, 2017) Bozdağ, Göksenin; Kuştepeli, AlpIn this study, a compact dual-band grounded coplanar waveguide fed printed planar monopole antenna (GCPW-PPMA) is designed and realized for Bluetooth, WLAN and WiMAX applications. Antenna is designed in two stages and a low-cost FR4 substrate is used. Firstly, a GCPW fed trapezoidal shape printed monopole radiator patch is designed at 5.8 GHz band and its bandwidth is improved by employing an inset. In the second phase, two different slot geometries are employed to excite 2.45 GHz band. Slot loadings, radiating patch and inset feeding are optimized and the dimensions of the resulting antenna are obtained as 25mm x 27.5 mm. Simulated and measured results are in good agreement, and measured operating bands of the proposed antenna are 2.40 GHz-2.52 GHz and 3.76 GHz-5.875 GHz for S-11 < -10 dB. The proposed GCPW-PPMA has dipole like radiation patterns in the operating bands. Its measured realized gains are 1 dB at 2.45 GHz and 2.5 dB at 5.8 GHz. The proposed antenna is suitable for space and weight limited portable devices.Article Citation - WoS: 2Citation - Scopus: 2Investigating the Experimental Limits of the Brewster’s Angle Method(Türkiye Klinikleri Journal of Medical Sciences, 2018) Sümer, Can; Kuştepeli, Alp; Dinleyici, Mehmet SalihWe present the method, analysis, and experimental results of the Brewster’s angle method commonly used for determining the refractive indices of optical films. We show the significance of the intersection of reflectance curves, in that the necessity for substrate refractive index and film layer thickness knowledge are both eliminated. We present the conditions for the existence of the second intersection of reflectance curves and introduce a method for determining the refractive index of the substrate layer by using the angular information alone. Analytical results reveal impressive practical sensitivity and accuracy limits for the method, where the experimental results also support the theoretical analysis.Article Citation - WoS: 5Citation - Scopus: 6Novel Square Spiral Antennas for Broadband Applications(Walter de Gruyter GmbH, 2009) Saynak, Uğur; Kuştepeli, AlpAn investigation of novel square spiral antennas is presented. The antennas are designed by considering the special arrangements of spiral arms. The new designs perform much better in terms of the frequency independency of the fundamental antenna parameters, when compared with the well known and widely used Archimedean spiral antenna, which makes the antennas very suitable for broadband wireless applications. Experimental results are also presented and there is a good agreement between the measured and numerical data.Conference Object Citation - WoS: 1Citation - Scopus: 1High Frequency Diffraction of Cylindrical Waves by Perfectly Conducting Successive Step Discontinuities(Institute of Electrical and Electronics Engineers Inc., 2006) Türetken, B.; Alkumru, Ali; Büyükaksoy, A.; Kuştepeli, AlpThe diffraction of high frequency cylindrical electromagnetic waves by step discontinuities is investigated rigorously by using the Fourier transform technique in conjunction with the mode matching method. The hybrid method of formulation gives rise to a scalar Wiener-Hopf equation of the third kind, the solution of which contains infinitely many constants satisfying infinite systems of linear algebraic equations.Other Citation - WoS: 2Citation - Scopus: 1Erratum To: Multi-Band Cpw Fed Mimo Antenna for Bluetooth, Wlan, and Wimax Applications(John Wiley and Sons Inc., 2017) Deste, İrem; Bozdağ, Göksenin; Kuştepeli, AlpIn the above-mentioned article, which appeared in Microwave and Optical Technology Letters, Volume 58#9, DOI 30001, the captions for Figure 1 and Figure 4 were published incorrectly. The corrections are shown below: Figure 1 Element antenna (a) Geometry (b) Fabricated (a = 12.5 mm, b = m = v = o = 0.5 mm, c = 4 mm, d = n = 15 mm, e = h = 3 mm, f = 14 mm, g = 16 mm, i = 7 mm, k = 1.5 mm, l = 12 mm, p = 1.25 mm, r = 1.64 mm, s = 1.7 mm, t = 1.94 mm, u = 11.1 mm, w = 0.3 mm). [Color figure can be viewed at wileyonlinelibrary.com] Figure 4 Fabricated MIMO antenna (d1 = d3 = 7 mm, d2 = 10 mm, d4 = 12 mm). [Color figure can be viewed at wileyonlinelibrary.com] In addition, Figure 6 was published with an error. The corrected figure is shown below: The publisher regrets any confusion caused by these errors. (Figure presented.).Other Citation - WoS: 1Erratum: Wideband Planar Monopole Antennas for Gps/Wlan and X-Band Applications (microwave and Optical Technology Letters 58:2)(John Wiley and Sons Inc., 2016) Bozdağ, Göksenin; Kuştepeli, AlpArticle Citation - WoS: 32Citation - Scopus: 41Subsectional Tapered Fed Printed Lpda Antenna With a Feeding Point Patch(Institute of Electrical and Electronics Engineers Inc., 2016) Bozdağ, Göksenin; Kuştepeli, AlpIn this letter, a log-periodic dipole array (LPDA) antenna operating between 1.1 and 13.8 GHz with VSWR < 2and an average peak realized gain of 5.2 dB is presented. It is suitable for GPS (L1-L5), PCS, IMT-2000, Bluetooth, WLAN, WiMAX, UWB, and X-band applications. The antenna is designed by introducing a subsectional tapered feedline instead of standard microstrip feeding, which leads to a remarkable lower-frequency performance. The upper-frequency performance of the antenna is improved by adding a feeding point patch. The group delay is also examined for the final design, and maximum 1.5 ns deviation is observed in UWB. By using ordinary and simple dipoles with this modified feedline approach, a superior antenna performance is obtained over a very wide frequency band, and it is validated by the comparison of three fabricated antennas. Additionally, the antenna size is also reduced without using complicated and/or top-loaded dipole structures.Article Citation - WoS: 5Citation - Scopus: 9Wideband Planar Monopole Antennas for Gps/Wlan and X-Band Applications(John Wiley and Sons Inc., 2016) Bozdağ, Göksenin; Kuştepeli, AlpIn this article, two printed planar monopole antennas (PPMA) are presented. In the design of the first PPMA, the structure is divided into sections and they are optimized in the sense of bottom to up strategy. Tapered transitions and inset feed are employed to increase the bandwidth. The antenna operates between 2.37 GHz and 12 GHz with VSWR<2 and an average peak realized gain of 4.95 dB. Therefore, it is suitable for WLAN, WiMAX, UWB, and X-Band applications. The second PPMA is designed by implementing slots on the previous one to include GPS. The resulting antenna operates in the 1.38-1.60 GHz and 2.33-13.74 GHz bands with VSWR<2. As a result, it also includes GPS in addition to the previous bands. The peak realized gain in GPS is 0.47 dB at 1.575 GHz and the average peak realized gain is 4.41 dB for the 2.33-13.74 GHz band. The group delay performances of the proposed PPMAs are also examined and the maximum group delay deviations of the first and the second PPMAs are observed as 1 ns and 1.33 ns, respectively.Article Citation - WoS: 10Citation - Scopus: 10On the Helmholtz Theorem and Its Generalization for Multi-Layers(Taylor and Francis Ltd., 2016) Kuştepeli, AlpThe decomposition of a vector field to its curl-free and divergence-free components in terms of a scalar and a vector potential function, which is also considered as the fundamental theorem of vector analysis, is known as the Helmholtz theorem or decomposition. In the literature, it is mentioned that the theorem was previously presented by Stokes, but it is also mentioned that Stokes did not introduce any scalar and vector potentials in his expressions, which causes a contradiction. Therefore, in this article, Stokess and Helmholtzs representations are examined in detail to reveal and emphasize their differences, similarities and important points. The Helmholtz theorem is obtained for all kinds of spaces by using the theory of distributions in a comprehensive and rigorous manner with detailed explanations, which also leads to a new surface version of the Helmholtz theorem or a new surface decomposition, resulting in the canonical form; hence, it is different than the one suggested previously in terms of two scalar functions. The generalized form of the Helmholtz theorem is also presented by employing the same approach when there is a multi-layer on the surface of discontinuity, which also corresponds to the extension of the theorem to fields with singularities of higher order.Article Citation - WoS: 13Citation - Scopus: 18Multi-Band Cpw Fed Mimo Antenna for Bluetooth, Wlan, and Wimax Applications(John Wiley and Sons Inc., 2016) Desde, İrem; Bozdağ, Göksenin; Kuştepeli, AlpIn this letter, multi-band coplanar waveguide (CPW) fed multiple-input-multiple-output (MIMO) antenna is presented for Bluetooth, WLAN and WiMAX applications. The elements of MIMO antenna are identical CPW-fed printed monopole antennas whose bandwidth performances are improved by employing inverse U and meander line slots. In the design of the antennas, a low-cost FR4 substrate is used and the size of the element antennas are optimized as 35 mm x 30 mm. According to the measurements, S11 is below −10 dB in 2.38 GHz – 2.52 GHz and 3.19 GHz – 6.44 GHz bands with 0.2 dB and 2.9 dB average peak realized gains, respectively. The element antennas are placed orthogonally and fed independently to obtain MIMO structure whose size is optimized as 42 mm x 62 mm. The performance of MIMO antenna is also examined in terms of diversity parameters such as envelope correlation coefficient and apparent diversity gain, which are lower than 0.02 and higher than 9.9 in the operating bands, respectively.