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

Bilgiç, M.M. | Yegin, K.

Article | 2013 | International Journal of Distributed Sensor Networks2013 , pp.296 - 304

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 Daha fazlası Daha az

Yegin, K.

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 Daha fazlası Daha az

Bilgic, M.M. | Yegin, K.

Erratum | 2013 | Microwave and Optical Technology Letters55 ( 8 ) , pp.4775 - 4782

[No abstract available]

Koc, G. | Yegin, K.

Article | 2013 | International Journal of Distributed Sensor Networks2013 , pp.4775 - 4782

Seismic sensors are invaluable for intruder detection and perimeter security. In a typical wireless sensor network application of seismic sensors, the units are battery powered and low power consumption becomes critical while fulfilling system requirements. Although many systems utilize 24-bit ADC for seismic signal processing, we employed 12-bit ADC for low power consumption. Because of this relatively low resolution ADC, preamplifier and filters require careful hardware design. We employ bidirectional T-type filtering, noise reduction, and distributed filtering between gain stages before the signal is input to ADC. The proposed de . . .sign was verified with measurements. Seismic data signals due to footsteps at varying distances were successfully measured. © 2013 Gokhan Koc and Korkut Yegin Daha fazlası Daha az

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.4775 - 4782

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

Isenlik, T. | Yegin, K.

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

https://hdl.handle.net/20.500.11831/1322

Koç, G. | Yegin, K.

Article | 2013 | International Journal of Distributed Sensor Networks2013 , pp.392 - 412

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

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.

Bilgic, M.M. | Yegin, K.

Article | 2013 | Microwave and Optical Technology Letters55 ( 6 ) , pp.1291 - 1295

Aperture coupled microstrip antenna is presented for Ku band phased-array applications. We show that radial open circuit terminated microstrip feed and hourglass aperture shape provide better coupling, high gain, wide bandwidth and small in-band gain variation. Eight-element antenna array with fixed beam tilt is formed and measured to validate simulations. Copyright © 2013 Wiley Periodicals, Inc.

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

Conference Object | 2013 | Proceedings of SPIE - The International Society for Optical Engineering8714 , pp.1291 - 1295

Detection of landmines based on complex resonance frequencies has been studied in the past and no distinctive results have been reported. Especially for low metal content landmines buried at depths greater than 9 cm, resonant frequencies become fairly distributed in the background and no specific frequency of interest can be used. However, in a typical impulse radar, spectral energy density of the transmitted pulse can be very broad and its peak can be located anywhere. Usually, a compromise is made between penetration depth and feature resolution for spectral energy peak allocation. Pulse amplitude, duration, symmetry, its spectral . . . energy distribution, ringing level all affect depth and resolution metrics in a complicated way. Considering receiver dynamic range, we study two distinct pulses having different spectral energy density peaks and their detection ability for landmines with little or no metallic content. We carry out experiments to show that pulse shape/fidelity is critical to obtain desired contrast in post-processing of data. © 2013 SPIE Daha fazlası Daha az

Koç, G. | Yegin, K.

Article | 2013 | International Journal of Distributed Sensor Networks2013 , pp.1291 - 1295

An algorithm is developed for footstep, vehicle, and rain detection using seismic sensors operating in a wireless sensor network. Each standalone seismic sensor is coupled with a wireless node, and alarm conditions were evaluated at the sensor rather than at the gateway. The algorithm utilizes slow and quick adaptive thresholds to eliminate static and dynamic noise to check for any disturbance. Duration calculation and filters were used to identify the correct alarm condition. The algorithm was performed on preliminary field tests, and detection performance was verified. Footstep alarm condition up to 8 meters and vehicle presence a . . .larm condition up to 50 meters were observed. Presence of rain did not create any alarm condition. Detection based on kurtosis was also performed and shortcomings of kurtosis especially for vehicle detection were discussed, proposed algorithm has minimal load on the sensor board and its data processing unit; thus, it is energy efficient and suitable for wireless sensor alarm networks. © 2013 Gökhan Koç and Korkut Yegin Daha fazlası Daha az