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.

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.

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 Daha fazlası Daha az

Bilgic, M.M. | Yegin, K.

Article | 2014 | IEEE Antennas and Wireless Propagation Letters13 , pp.157 - 160

A high-gain, wideband antenna element that covers most portions of X-and Ku-bands is essential for multimode radar applications. This letter presents an aperture-coupled stacked patch antenna for 8.75-12.25-GHz frequency band. Fixed beam tilt up to 30^ in scan range can be obtained by offsetting the aperture relative to a driven patch. When there is no offset, a single antenna has broadside gain greater than 10 dBi. An antenna array (4×,4) with fixed beam tilt is designed and validated with measurements. The prototype antenna exhibits 44% fractional bandwidth and maximum gain 20.6 dBi in the target frequency band. © 2014 IEEE.

Bilgic, M.M. | Yegin, K.

Article | 2014 | IEEE Transactions on Antennas and Propagation62 ( 4 ) , pp.2258 - 2263

Wideband, planar and low profile antenna array is proposed and designed for Ku band direct broadcast from satellite reception for mobile systems. Contrary to earlier designs, the array antenna covers entire downlink Ku-band frequencies (10.8-12.75 GHz) for simultaneous reception from multiple transponders. The array antenna exhibits 16.5% bandwidth and has 30 dBi average gain for both vertical and horizontal polarizations. To achieve high efficiency, hybrid waveguide microstrip feed network is proposed. H-plane waveguide T-junctions with reduced waveguide height and disk loaded coaxial probe for microstrip to waveguide transition ar . . .e designed. Loss in the array is formulated as an optimization problem and it is minimized for subarray and array configuration. Overall height of the planar antenna with waveguide feed network is under 25 mm. The antenna is built and tested for reception quality. Carrier-to-noise ratio of 9.5 dB was observed for the target transponder (42°E) at 11.9 GHz using IF loop-out of the receiver. © 1963-2012 IEEE Daha fazlası Daha az

Yegin, K. | Kavak, A. | Cayirci, E. | Dandekar, K.

Editorial | 2014 | International Journal of Distributed Sensor Networks2014 , pp.2258 - 2263

[No abstract available]

Yesil, M.A. | Yegin, K. | Bellikli, H. | Tura, L. | Nazlg, H. | Dag, M.

Conference Object | 2014 | Proceedings of SPIE - The International Society for Optical Engineering9072 , pp.2258 - 2263

Metal detector coil design has been matured to great extent over the years. However, vehicle mounted or remotely operated metal detectors require different specifications and these specifications dictate multiple transmit and receive coils operating in various settings. Unlike handheld operation, detector is more susceptible to metallic body of the vehicle. Moreover, ground calibration is also different than handheld devices. Coil geometries and intercoupling between them play a significant role in system design and performance. In this study, we study different coil geometries for vehicular applications. Starting from well-known co . . .il geometries, we placed coils on dry, wet and ferrous soil to understand the interaction mechanism. Simulation studies are performed in frequency domain but the results are all applicable to time domain pulse based detector systems. © 2014 SPIE Daha fazlası Daha az

Giral, A. | Kurt, R. | Yegin, E.G. | Yegin, K.

Article | 2014 | Diseases of the Esophagus27 ( 3 ) , pp.206 - 213

An accurate reflux-symptom relationship analysis method is an unmet need in gastroesophageal reflux disease (GERD) diagnosis. The aim of this study was to adapt signal detection theory (SDT) approach to reflux-symptom relationship analysis to develop a new diagnosis method. Patients with predominant symptoms of heartburn and regurgitation were enrolled. Proton pump inhibitor (PPI)-responsive and PPI-unresponsive groups were created via interview and PPI trial. Patients then underwent stationary esophageal manometry and 24-hour multichannel intraluminal impedance-pH monitoring. SDT measurement parameters (discriminability: d' and cri . . .terion: c) were calculated using empirically selected time windows (0.5, 1, 2, 3, 4 and 5 minutes). The time window that provided the highest d' value was selected as the optimal time window. A cut-off d' value that optimally separates two groups was found using receiver operating characteristics analysis. Sixty-three patients completed the study (45 PPI responsive). Optimal time window and cut-off d' value were found as 1 and 0.767 minute, respectively. Symptom association probability (SAP) index values showed good correlation (rS = 0.7182, P < 0.0001) with d' values. SDT approach to reflux-symptom relationship analysis showed sensitivity (89% vs. 78%) and negative predictive values (75% vs. 60%) favorable over SAP index analysis. SDT approach using 1-minute time window and 0.767 cut-off d' value provides us a new and more accurate measure of reflux-symptom relationship than SAP index analysis. © 2013 Wiley Periodicals, Inc. and the International Society for Diseases of the Esophagus Daha fazlası Daha az