Nassor, M.A. | Korkmaz, E. | Yegin, K.
Conference Object | 2014 | 2014 31th URSI General Assembly and Scientific Symposium, URSI GASS 2014
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.
Araz, I. | Dursun, A. | Demirci, E. | Korkmaz, E. | Yegin, K.
Conference Object | 2011 | 2011 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011
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
Biçak, E. | Yegin, K. | Nazli, H. | Dag, M.
Conference Object | 2014 | Proceedings of SPIE - The International Society for Optical Engineering9077
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.
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
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
Şişman, I. | Yegin, K.
Article | 2017 | International Journal of Antennas and Propagation2017 , pp.296 - 304
We propose a simple solution for jamming mitigation of L1 band GPS by electronically switching antenna beam for wide and narrow beamwidths. Assuming the jamming signal is directed from low elevation angles, antenna reception can be made significantly lower at these angles by electronically reconfiguring the antenna beamwidth. Four-element antenna array and one of the elements of the array are designated as antijam (array) mode and normal mode of the antenna. The antenna is placed on a degenerate-ground with symmetric slots in the ground. Front-end configuration for this antenna is also discussed. Simulations and measurements are per . . .formed to validate the proposed design. The antenna achieves more than 15 dB rejection in measurements and more than 20 dB cross-polarization improvement compared to standalone (normal mode) antenna. The system can easily be replaced with existing active antenna to improve antijam capability of the receiver. © 2017 İsmail Şişman and Korkut Yegin
Bayrakceken, F. | Yegin, K. | Korkmaz, E. | Bakis, Y. | Unal, B.
Article | 2012 | International Journal of Photoenergy2012 , pp.296 - 304
Polycyclic aromatic hydrocarbon compound, 1,2: 3,4-dibenzanthracene, is spectroscopically analyzed in ethanol. Ultraviolet absorption spectra were taken and fluorescence measurements were performed. From absorption and emission spectra, Stokes' lines were clearly discernible and these shifts were recorded. Being a carcinogenic compound, the detection of 1,2: 3,4-dibenzanthracene presence in the environment as a pollutant with adverse genotoxic effects is vital. © 2012 Fuat Bayrakceken et al.
Yigit, O. | Asci, Y. | Sissman, I. | Yegin, K.
Conference Object | 2017 | 24th Telecommunications Forum, TELFOR 2016 , pp.296 - 304
We propose a low-cost solution for jamming mitigation of GPS by electronically switching antenna beam. Jamming signals are assumed to be directed from low elevation angles so that antenna rejection from zenith to low elevation must be improved by switching from wide angle half power beam width to a narrow one. Using low-cost, commercially available ceramic patches, four-element antenna array and its feed network are designed and one of the elements is designated as the normal (default) mode operation of the antenna. Proposed system can easily be replaced with existing active antenna to improve anti-jam capability of the receiver. © . . .2016 IEEE
Tas, M. | Dasdag, S. | Akdag, M.Z. | Cirit, U. | Yegin, K. | Seker, U. | Eren, L.B.
Article | 2014 | Electromagnetic Biology and Medicine33 ( 3 ) , pp.216 - 222
The purpose of this study is to bridge this gap by investigating effects of long term 900 MHz mobile phone exposure on reproductive organs of male rats. The study was carried out on 14 adult Wistar Albino rats by dividing them randomly into two groups (n: 7) as sham group and exposure group. Rats were exposed to 900 MHz radiofrequency (RF) radiation emitted from a GSM signal generator. Point, 1 g and 10 g specific absorption rate (SAR) levels of testis and prostate were found as 0.0623 W/kg, 0.0445 W/kg and 0.0373 W/kg, respectively. The rats in the exposure group were subject to RF radiation 3 h per day (7 d a week) for one year. F . . .or the sham group, the same procedure was applied, except the generator was turned off. At the end of the study, epididymal sperm concentration, progressive sperm motility, abnormal sperm rate, all-genital organs weights and testis histopathology were evaluated. Any differences were not observed in sperm motility and concentration (p > 0.05). However, the morphologically normal spermatozoa rates were found higher in the exposure group (p < 0.05). Although histological examination showed similarity in the seminiferous tubules diameters in both groups, tunica albuginea thickness and the Johnsen testicular biopsy score were found lower in the exposure group (p < 0.05, p < 0.0001). In conclusion, we claim that long-term exposure of 900 MHz RF radiation alter some reproductive parameters. However, more supporting evidence and research is definitely needed on this topic. © 2014 Informa Healthcare USA, Inc. All rights reserved: reproduction in whole or part not permitted
Bilgiç, M.M. | Yegin, K.
Article | 2013 | International Journal of Distributed Sensor Networks2013 , pp.216 - 222
Polarization reconfigurable microstrip patch antenna is presented for 2.4-2.5 GHz wireless sensor network and WLAN applications. Dual feed degenerate mode patch is used as the starting point for circular polarization and L-shaped islands which can be connected or disconnected to the main patch via RF switches are placed around the patch. When L-shape structure is connected, the patch radiates in linear polarization modes with either vertical or horizontal polarization depending on the feed being used. When RF switches are not biased, the antenna is in circular polarization mode. Full wave simulations and measurements were carried ou . . .t to validate the design. © 2013 Mustafa Murat Bilgiç and Korkut Yegin
Article | 2013 | IEEE Transactions on Antennas and Propagation61 ( 9 ) , pp.4775 - 4782
A diversity antenna system with antennas embedded in rear view mirrors of a vehicle is proposed for satellite digital audio radio system. Antenna diversity is needed because hidden antennas exhibit limited capability and composite body vehicles have poor reception due to no ground plane availability. Pattern gain diversity achieved with the proposed system is proven with on-vehicle antenna simulations and gain measurements. Selection combining diversity receiver architecture is also proposed and the system is tested in real time under two fading scenarios: weak satellite signal in dense foliage and multipath terrestrial environment . . .with frequent satellite blockages. In both cases, the diversity system outperformed the reference antenna system with less mutes times (0.6% versus 0.8% in multipath, 0.1% versus 0.25% in dense foliage) and Reed-Solomon block errors (1.75% versus 2.18% in multipath, 0.87% versus 1.18% in dense foliage). The proposed rear-view mirror location is ideal for minimum signal degradation compared to windshield, backlite, and dashboard antenna installations. © 1963-2012 IEEE
Bilgic, M.M. | Yegin, K.
Erratum | 2013 | Microwave and Optical Technology Letters55 ( 8 ) , pp.4775 - 4782
[No abstract available]