Bulunan: 45 Adet 0.001 sn
Koleksiyon [4]
Tam Metin [1]
Yazar [20]
Yayın Türü [4]
Konu Başlıkları [20]
Yayın Tarihi [9]
Dergi Adı [19]
Yayıncı [9]
Dil [1]
Yazar Departmanı [1]
Derivation of Green's Functions for Paraxial Fields of a Wedge with Particular Anisotropic Impedance Faces

Isenlik, T. | Yegin, K.

Article | 2013 | Electromagnetics33 ( 5 ) , pp.392 - 412

Millimeter wave detection of landmines

Öztürk, H. | Nazli, H. | Yegin, K. | Biçak, E. | Sezgin, M. | Dag, M. | Türetken, B.

Conference Object | 2013 | Proceedings of SPIE - The International Society for Optical Engineering8709 , pp.392 - 412

Millimeter wave absorption relative to background soil can be used for detection landmines with little or no metal content. At these frequencies, soil and landmine absorb electromagnetic energy differently. Stepped frequency measurements from 20 GHz to 60 GHz were used to detect buried surrogate landmines in the soil. The targets were 3 cm and 5 cm beneath the soil surface and coherent transmission and reflection was used in the experimental setup. The measurement set-up was mounted on a handheld portable device, and this device was on a rail for accurate displacement such that the rail could move freely along the scan axis. Measure . . .ments were performed with network analyzer and scattering data in frequency domain were recorded for processing, namely for inverse Fourier Transform and background subtraction. Background subtraction was performed through a numerical filter to achieve higher contrast ratio. Although the numerical filter used was a simple routine with minimal computational burden, a specific detection method was applied to the background subtracted GPR data, which was based on correlation summation of consecutive A-scan signals in a predefined window length. © 2013 SPIE Daha fazlası Daha az

Micro size detector antennas at 30 THz

Nassor, M.A. | Korkmaz, E. | Yegin, K.

Conference Object | 2014 | 2014 31th URSI General Assembly and Scientific Symposium, URSI GASS 2014 , pp.392 - 412

Planar antennas such as microstrip patch, bowtie, spiral, and modified crossed dipole are designed and simulated at 30 THz. Gains of antennas obtained directly from simulation results are verified using a different technique inspired from radar cross section measurements. Reradiated far field of an antenna when its feed point is open-circuited is obtained with a far-field probe. The proposed method is introduced as an alternative for the signal detection sensitivity measurements of IR detector antennas. © 2014 IEEE.

Simulation of an 18-vane magnetron in CST-PIC

Araz, I. | Dursun, A. | Demirci, E. | Korkmaz, E. | Yegin, K.

Conference Object | 2011 | 2011 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011 , pp.392 - 412

This paper presents the simulation of a vane-type magnetron using the commercial electromagnetic software Particle-in-Cell (PIC) solver in CST. The magnetron mainly consist of 18 anode vanes without strap. The resonance frequency has been selected in X band since it has a long production history enabling a ready comparison of computed and measured results. Simulation of magnetrons has been improved by changing dimensions of cavities, optimizing voltage and applied magnetic fields values. The aim of this work is to tune the operation frequency of magnetron under the constant electric field and the magnetic field between the anode and . . . cathode. © 2011 IEEE Daha fazlası Daha az

Tapered slot antenna design for vehicular GPR applications

Biçak, E. | Yegin, K. | Nazli, H. | Dag, M.

Conference Object | 2014 | Proceedings of SPIE - The International Society for Optical Engineering9077 , pp.392 - 412

Vehicular applications of UWB GPR demand multiple GPR sensors operating in a harsh environment. One of the key elements of in the sensor is its UWB antenna which has minimal inter-element coupling, low group delay, high directivity and less prone to environmental conditions. Tapered slot antennas (TSA's) provide good impedance match, but they need to be modified for above specifications. Parasitic slot loaded TSA with balanced feed is proposed and a multi-channel antenna array structure is formed. Structural parameters are numerically analyzed and a prototype is built. Measurements show good performance for UWB GPR applications. © 2014 SPIE.

Tutorial on the design of hole-slot-type cavity magnetron using CST particle studio

Isenlik, T. | Yegin, K.

Article | 2013 | IEEE Transactions on Plasma Science41 ( 2 ) , pp.296 - 304

We present a simple design method for the hole-slot-type cavity magnetron. Our design model includes all principal parts of magnetron, namely, the cathode, the resonant system, the interaction space, and the magnetic circuit. We first find structural, electrical, and magnetic parameters using empirical formulas. Then, using empirical values as initial guesses, we build and simulate the 3-D model of magnetron in CST Particle Studio. In CST, we show that the eigenmode solver is essential for proper mode excitation; then, we use particle tracking and particle-in-cell simulations for the desired magnetron operation. For a fast convergen . . .t result, we study the impact of design parameters on the magnetron performance. We apply this design procedure to an X-band hole-slot-type magnetron with eight resonators. We believe that our method provides designers a simple, fast, and reliable tool for hole-slot-type magnetron design. © 2012 IEEE Daha fazlası Daha az

Measurements of signal penetration into mock missiles

Kocakarin, I. | Yegin, K.

Conference Object | 2017 | 2017 4th International Electromagnetic Compatibility Conference, EMC Turkiye 2017 , pp.296 - 304

Signal penetration into missiles through nose cone and apertures is critical for electro-optical guidance systems, navigation equipment and control of explosive ordnance. Penetrated signals are relatively small but hard to simulate by known computational methods. To corroborate simulation results, we created a scaled version of a missile and placed wire antennas inside this mock missile. The prototype has openings on the nose cone. Measurements are performed for different antenna sizes placed inside the nose cone. These measurements, then, are compared to numerically calculated simulation results. The extent of corroboration and pos . . .sible ways to improve correct prediction of signal coupling are discussed. © 2017 IEEE Daha fazlası Daha az

Gain-bandwidth product for aperture-coupled antennas

Bilgiç, M.M. | Yegin, K.

Conference Object | 2013 | 2013 Computational Electromagnetics Workshop, CEM 2013 , pp.21 - 22

Bandwidth, gain, and HPBW are the most essential design characteristics in antenna design. Other features such as cross polarization ratio, front-to-back ratio, in-band gain ripple, electrical height, and physical dimensions also play a critical role in the design. It is difficult to define a common figure-of-merit (FOM) that includes all these metrics, but we present several FOM applicable for aperture coupled antennas. Various nonresonant and resonant slot coupled stacked patches are compared to each other to identify the best configuration. Integral equation based solver is used in the computational analysis.

Paraxial fields of a wedge with anisotropic impedance and perfect electric conductor faces excited by a dipole

Isenlik, T. | Yegin, K.

Article | 2010 | Electromagnetics30 ( 7 ) , pp.589 - 608

A three-dimensional dyadic Green's function is derived for electromagnetic scattering due to a point electric current source radiating in the vicinity of a wedge with anisotropic impedance and perfect electric conductor faces. The anisotropic impedance face is characterized by surface impedances along directions parallel and orthogonal to the edge axis (principal anisotropy axis). Arbitrary surface impedance is assumed in one direction only (either parallel or orthogonal to principal anisotropy axis), and vanishing impedance is assumed on the other. Assuming reactive surface impedance, the derived forms involve a summation over an a . . .ngular wavenumber and a longitudinal spectral integral, which may be evaluated asymptotically to describe the fields in paraxial region, where the source and observation points are in close proximity to the apex but widely separated. The final asymptotic result reveals three different scattering mechanisms: edge-guided waves, surface waves, and guided waves in the classical sense. Numerical simulations are performed for capacitive and inductive surfaces using the asymptotic results. Simulation results are also compared to those of a commercially available electromagnetic field solver, which assumes uniform surface impedance. Copyright © Taylor & Francis Group, LLC Daha fazlası Daha az

Footstep and vehicle detection using seismic sensors in wireless sensor network: Field tests

Koç, G. | Yegin, K.

Article | 2013 | International Journal of Distributed Sensor Networks2013 , pp.589 - 608

Extensive field tests were carried out to assess the performance of adaptive thresholds algorithm for footstep and vehicle detection using seismic sensors. Each seismic sensor unit is equipped with wireless sensor node to communicate critical data to sensor gateway. Results from 92 different test configurations were analyzed in terms of detection and classification. Hit and false alarm rates of classification algorithm were formed, and detection ranges were determined based on these results. Amplification values of low-intensity seismic data were also taken into account in the analysis. Algorithm-dependent constants such as adaptive . . . thresholds sample sizes were examined for performance. Detection and classification of seismic signals due to footstep, rain, or vehicle were successfully performed. © 2013 Gökhan Koç and Korkut Yegin Daha fazlası Daha az

Prompt and delayed fluorescences

Yegin, K. | Karaaslan, Ş.I. | Aslan, N.

Editorial | 2012 | International Journal of Photoenergy2012 , pp.589 - 608

[No abstract available]

Surface plasmon-enhanced nanoantenna for localized fluorescence

Kocakarin, I. | Yegin, K.

Article | 2012 | International Journal of Antennas and Propagation2012 , pp.589 - 608

Surface plasmon-enhanced gold nanoantenna structures on glass substrate are studied for increased localized electric field and fluorescence at the feed gap locations of the antennas. Dipole, Archimedean balanced spiral, and bowtie and double bowtie geometries are studied for surface plasmon effect. Different flare angles for bowtie geometries are compared to each other. Double bowtie geometry with dual polarization capability exhibited superior performance with almost 56 dB field enhancement factor. We also studied the effect of substrate thickness on electric field enhancement and we found that glass thickness plays a critical role . . . for coherent addition of surface plasmons at the feed gap location. The surface plasmon effect is proven by considering perfect electric conductor model of gold instead of its modified Drude model. © 2012 Isa Kocakarin and Korkut Yegin Daha fazlası Daha az

6698 sayılı Kişisel Verilerin Korunması Kanunu kapsamında yükümlülüklerimiz ve çerez politikamız hakkında bilgi sahibi olmak için alttaki bağlantıyı kullanabilirsiniz.

Bu site altında yer alan tüm kaynaklar Creative Commons Alıntı-GayriTicari-Türetilemez 4.0 Uluslararası Lisansı ile lisanslanmıştır.