Caner Özdemir - Academia.edu (original) (raw)

Papers by Caner Özdemir

El-Cezeri Fen ve Mühendislik Dergisi, 2021

In this study, the suspended pendulum system was controlled by PID (Proportional-Integral-Derivat... more In this study, the suspended pendulum system was controlled by PID (Proportional-Integral-Derivative). Obtaining the system parameters was carried out using the PSO (Particle Swarm Optimization) algorithm in the simulation environment. For this purpose, the model of the suspended pendulum system's model was created. The parameters of the real system were found through the model. Viscous damping coefficient, Moment of Inertia and PID coefficients were calculated as parameters. The calculated values were used in the real system and the real system proved the accuracy of simulation the model. Control of the system was carried out in PLC (Programmable Logical Controller). The force required for the pendulum to reach a certain position was obtained by brushless motor control. ESC (Electronic Speed Control) is used as brushless motor driver and PWM (Pulse Width Modulation) is used as control signal of ESC. The encoder is used to measure the position of the system. System data was obtained with MATLAB. Communication between MATLAB and PLC is realized with OPC (OLE for Process Control). End of the study, it was observed that the simulation and optimization algorithm and the control of the real system gave similar results.

This paper presents a simple method for determining the dielectric constant of microwave PCB subs... more This paper presents a simple method for determining the dielectric constant of microwave PCB substrates. In the presented method, a bandpass microstrip filter on the PCB substrate with a user-predicted dielectric constant value is designed for a given center frequency, and it is implemented. The simulation results of the designed bandpass filter are obtained by the help of electromagnetic analysis software; XFDTD. Experimental results regarding the filter frequency characteristic are accomplished by means of a vector network analyzer. The simulation results of the designed filter are modified to overlap with the experimental ones by varying the dielectric constant value. When the simulation and experimental results are overlapped, the value of dielectric constant is accurately selected. In order to illustrate the validity of proposed method, the dielectric constant values of flame resistant-4 (FR4) substrates are acquired at IEEE 802.11b/g and IEEE 802.11a wireless local area networ...

In this study, an efficient and practical approach is proposed to increase the bandwidth of narro... more In this study, an efficient and practical approach is proposed to increase the bandwidth of narrow-band antennas by designing lossless impedance matching network with the simplified real frequency technique. Our algorithm does not require prior knowledge of network analytical topology of the load impedance that is to be matched. Any frequency-dependent data such as antenna radiation data (either measurement or simulated) can be easily matched via the proposed algorithm. The matching network realized by this technique is relatively simple and gives superior gain properties compared to that obtained by other methods. The proposed method is tested with various data sets for different antenna configurations. The results validate the effectiveness and the success of the algorithm.

2009 International Conference on Electrical and Electronics Engineering - ELECO 2009, 2009

In this paper, a method for obtaining focused inverse synthetic aperture radar (ISAR) images of t... more In this paper, a method for obtaining focused inverse synthetic aperture radar (ISAR) images of targets based on the radar backscattering measurements taken over wide bands and wide angles. The proposed method divides wide angle and wide frequency band into small aperture bands in the spatial frequency or Fourier domain. This set-up makes it possible to use fast calculation of ISAR images for every sub-aperture data set as in the case of standard ISAR case of small-bandwidth and small-angle. The details of the method are presented and numerical examples are given for the validation the method. The electromagnetic scattering estimation from the target is calculated via a hybrid simulator that uses both the physical optics and the shooting & bouncing ray concepts.

The Turkish Online Journal of Distance Education, 2012

In recent years, strategic planning has become one of the subjects that many institutions work on... more In recent years, strategic planning has become one of the subjects that many institutions work on to ensure the intuitions’ appropriate management based on realistic results. Therefore, this planning has to be taken into account and should provide planning direction on the bases of its results. Basically, the manager of strategic planning, leadership and strategic thinking and to act to help planners designed the tools, processes and concepts is a group. At the same time, the organization of the development and effective strategies will help to place. The purpose of this research is to provide SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis and to present new suggestions based on the opinions of students in the distance education system. In this work, we have applied Survey Method. The study group has consisted of 70 students and 11 instructors of Mersin Vocational School of Higher Education (MVSHE). All the data was surveyed during the spring semester of 2009. In t...

In this paper, a compact and effective implementation of physical theory of diffraction (PTD) for... more In this paper, a compact and effective implementation of physical theory of diffraction (PTD) formulation is proposed. The PTD formulation is tailored to recently developed high-frequency radar cross section (RCS) prediction tool; Predics. This PTD implementation is unique such a way that it is specially tailored to shooting and bouncing ray (SBR) technique via ray tracing and field tracing techniques. The detailed derivation of this PTD implementation is formulated and the algorithm steps are given together with its inclusion to Predics. The success and the validity of the proposed PTD implementation to the ray-launching RCS simulator have been tested with several benchmark targets that have either analytical or measured RCS values. Simulated RCS results ensure the accuracy of the proposed diffraction formulation that has been attached to the SBR technique over the test targets given within the paper. To better assess the effect of diffraction phenomenon to the total RCS value, mor...

IEEE Access, 2020

An assessment of polarimetric inverse synthetic aperture radar (Pol-ISAR) imaging is accomplished... more An assessment of polarimetric inverse synthetic aperture radar (Pol-ISAR) imaging is accomplished for realistic target models with the use of our recently developed high-frequency radar cross-section simulator tool called PREDICS. X-band, narrow-angle and full-polarimetric ISAR data for the CAD models of the well-known test object SLICY and a ground vehicle, namely a backhoe loader are analyzed to infer their structural characteristics. Experimental data obtained from a tower-turntable ISAR measurements of a T-72 tank target have also been utilized to assess the validity of the simulator. First, the intensity images in linear and circular polarization bases are directly utilized to evaluate the data quality and to characterize target features for classification. Then, the Pauli image decomposition scheme is applied to separate the basic scattering mechanisms occurring at target pixels. The identifiable canonical target forms are successfully extracted as single, double and multi-bounce scattering mechanisms that are pinpointed at their true locations. The results indicate that PREDICS is able to generate high-fidelity synthetic Pol-ISAR signatures of complex targets whereby successful interpretation of innumerous target scattering mechanisms and features can be achieved through Pauli decomposition scheme for classification purposes. INDEX TERMS PREDICS radar cross-section (RCS) simulator, inverse synthetic aperture radar (ISAR), Pauli decomposition, polarimetric ISAR.

International Journal of Engineering and Geosciences, 2021

In this study, a multithreaded method for triangular mesh three-dimensional computer aided design... more In this study, a multithreaded method for triangular mesh three-dimensional computer aided design objects is proposed to detect and extract wedges. Wedge detection is time consuming process for such objects that have large number of facets. To take the advantage of parallel computing opportunities, the algorithm is refactored in this study. Scope of variables, memory management and stack use are optimized for efficient use of computational resources. The proposed method is focused to calculation efficiency and performance on multicore / multithreaded processors and it is evaluated with benchmark, complex and realistic objects.

International Journal of Engineering and Geosciences, 2020

In this study, a quantitative radar cross section (RCS) analysis of different unmanned aerial veh... more In this study, a quantitative radar cross section (RCS) analysis of different unmanned aerial vehicle (UAV) models were accomplished by means of a series of RCS simulations. The simulations were carried out by high-frequency RCS simulation and analysis tool called PREDICS. To quantify the RCS features of the UAV model, both the anglevariation and frequency-variation simulations for all polarization excitations were performed. The results of the simulations suggested that RCS values were dramatically varying with respect to look angle with some special angles providing the large values of RCS. Generally, the RCS values of the UAV model was increasing with frequency as expected. A quantitative radar detection range analyses were also accomplished to assess the visibility of both the military-type and civil-type UAV models. The outcome of these studies has suggested that large-size UAV model can be easily detected by a high-sensitive radar on the ranges of tens of kilometers while thes...

International Journal of Engineering and Geosciences, 2020

Inverse synthetic aperture radar (ISAR) imaging is a reliable detection and classification techni... more Inverse synthetic aperture radar (ISAR) imaging is a reliable detection and classification technique for maneuvering targets at near and far-field ranges. In this study, we examine the near-field circular (turntable) ISAR imaging by conducting various real measurement experiments that were performed in the microwave anechoic chamber of the Mersin University’s MEATRC laboratory. The backscattered data were collected via a vector network analyzer that works as a Stepped Frequency Continuous Wave (SFCW) radar and for a number of simple and complex metal objects. The collected raw data were calibrated by using the backscattering data of a canonical object and then focused by applying a near-field backprojection image reconstruction algorithm. The resultant circular ISAR images demonstrate successful and well localized detection of various types of targets even though they are camouflaged by clothing. The obtained results reveal the preliminary efficacy of C band ISAR imaging in conceale...

International Journal of Engineering and Geosciences, 2021

Ground-based synthetic aperture radar (GB-SAR) systems are mostly utilized to be practical practi... more Ground-based synthetic aperture radar (GB-SAR) systems are mostly utilized to be practical practices in improved understanding of the complex mechanism of microwave backscattering. They also provide complementary information on evaluating the validity of the polarimetric analysis of air-borne or satellite-borne SAR applications. This study investigates some capabilities of polarimetric L-band GB-SAR imaging by testing its performance against a typical terrain and various kinds of manmade targets. Trihedral corner reflectors are also included in the analyses because of their importance in data calibration. Polarimetric backscattering signatures of different targets are analyzed in terms of qualitative assessment of amplitude images and identification and classification of scattering mechanisms through target decomposition techniques. The findings of these analyses and detailed discussions are presented. Specifically, the entropy/mean-alpha ((H/α ̅)) classification results are shown t...

Journal of Electrical and Computer Engineering, 2017

An algorithm for detecting cavities inside a tree-body is presented with simulation and measured ... more An algorithm for detecting cavities inside a tree-body is presented with simulation and measured examples. The details of the imaging algorithm that is based on sinusoidal template focusing routine are given. First, the algorithm is tested with the simulation scenario for which perfect reconstruction of the simulated cavity structure together with tree-body is successfully formed in MATLAB programming environment. Then, the algorithm is applied to the measurement data that have been collected from a laboratory set-up. Collected backscattered measurements from the tree-body (with cavity) structure are used to generate the image of the scene by the help of our proposed algorithm. The resultant radar images of the measured data collected from the laboratory arrangement have shown the applicability of the developed algorithm for the detection of cavity structures inside tree-bodies.

Progress In Electromagnetics Research M, 2018

In this study, the scattering map of the breast is reconstructed by applying the matchingpursuit ... more In this study, the scattering map of the breast is reconstructed by applying the matchingpursuit algorithm (MPA) to the simulation data obtained by the monostatic inverse synthetic aperture radar (ISAR) principle, and the locations of the tumors are determined by considering the peaks on the scattering map. The MPA iteratively searches the true solution by assuming every discrete point in the solution space to be a scattering center by dividing the imaging region onto a discrete grid. In order to obtain images with better resolution, the fine granularity of the grid for accurate solutions is provided at the expense of increased processing times. First, our approach based on MPA is tested on simulated data generated by MATLAB for breast tumor detection and imaging. Perfect reconstruction for the locations of the hypothetical breast tumor points is attained. Then, a full-wave electromagnetic simulation software named CST Microwave Studio (CST MWS) is used to generate backscattered electric field data from a constructed scenario in which a tumor is located in a breast model. Next, we use the collected data from the defined scenarios as an input to our algorithm. Resultant images provide successful detection and imaging of the tumor region within the breast model. The accuracy of the MATLAB and the CST MWS simulation results demonstrate the availability of our MPA-based focusing algorithm to be used effectively in medical imaging.

Turkish Journal of Engineering, 2017

In this paper, we propose an ultrawide band design for the double ridged horn (DRH) antenna to be... more In this paper, we propose an ultrawide band design for the double ridged horn (DRH) antenna to be used behind the obstacle radar (BOR) applications such as ground penetrating radar (GPR) and through the wall radar (TWR) imaging. The design is developed and optimized by the help of full electromagnetic simulator code; CST. The design parameters such as frequencies of operation and the half power beam width (HPBW) are taken into account by considering the BOR application requirements. The design double ridged horn antenna provides a frequency bandwidth between 1.5 GHz and 7 GHz and HPBW around 30° around the center frequency that are very suitable for GPR and TWR applications. The final optimized design that is formed by CST is physically manufactured and measured. The prototyped DRH antenna’s measurement antenna parameter results are in good agreement with the simulated ones.

Progress In Electromagnetics Research B, 2008

It is well known in B-scan ground penetrating radar (GPR) imagery that the underground scatterers... more It is well known in B-scan ground penetrating radar (GPR) imagery that the underground scatterers generally exhibit defocused, hyperbolic characteristics. This is mainly due to the data collection scheme and the finite beam width of the main lobe of the GPR antenna. To invert this undesirable effect and obtain focused images, various migration or focusing algorithms have been developed. In this paper, we survey the performance of our recent focusing algorithms, namely; hyperbolic summation (HS) and frequency-wavenumber (w-k) based synthetic aperture radar (SAR) focusing. The practical usage of these focusing methods were tested and examined on both simulated and measured GPR data of various buried targets. The simulation data set is obtained by a physical optics shooting and bouncing ray (PO-SBR) technique code. Measurements were taken by a stepped frequency continuous wave (SFCW) radar setup. Scattered C-band field data were measured from a laboratory sand box and from outdoor soil environment. The proposed focusing methods were then applied to the B-scan GPR images to enhance the resolution quality within these images. The resultant GPR images obtained with the proposed algorithms demonstrate enhanced lateral resolutions.

The capacity of forward link (FL) communication to mobile receivers is limited primarily by co-ch... more The capacity of forward link (FL) communication to mobile receivers is limited primarily by co-channel interference (CCI). Adaptive Antenna Arrays (AAAs) that employ antenna arrays along with advanced signal processing at the base station (BS) have been proposed to mitigate this limitation. We present FL capacity analysis for mixed voice and data user traffic scenarios in third generation (3G) CDMA cellular network, where each BS is equipped with either three-sector uniform linear array (ULA) or non-sectorized uniform circular array (UCA). We demonstrate that the FL capacity of the system is considerably affected by the antenna array topology. We find that the optimum element spacing resulting in the largest FL system capacity is 0,5 for both ULA and UCA topologies. Also, it is found that the UCA provides larger FL capacity when compared to the ULA under the same array parameters, i.e., element spacing and number of elements per cell.

In this work, several cancellation techniques for undesired clutter in various SAR images are pre... more In this work, several cancellation techniques for undesired clutter in various SAR images are presented. As a good example of SAR imagery, publicly released MSTAR images are taken as the practical application. The modelling of clutter is done by probabilistic approach. Target detection techniques including CFAR (Constant False Alarm Rate) is applied. To find the best fit for the background clutter, higher-order statistics are implemented and various distributions from Rayleigh to Weibull are tested. By using adaptive threshold CFAR detectors MSTAR targets are effectively segmented from clutter backgrounds.

A comparativestudy on the performance of the computational electromagnetic methods (CEMs) namely ... more A comparativestudy on the performance of the computational electromagnetic methods (CEMs) namely finite difference time domain (FDTD), finite element method (FEM) and moment method (MoM) via their corresponding electromagnetic softwarehas been presented forC, E, H and Lshaped compact microstrip antennas (CMAs)constructed by slot-loading the rectangular patch. For this purpose, the antennas were simulated with the use of CEMs and fabricated by using Rogers RT/duroid 5870 materials. The simulations were then compared with the measurements with respect to the return loss curves (s 11). The comparative results have been presented to illustrate the conformity rate between the simulations and measurement in term of the resonant frequency of 10-dB bandwidth.

2011 XXXth URSI General Assembly and Scientific Symposium, 2011

The detection of concealed objects like weapon, explosives, and other dangerous items became very... more The detection of concealed objects like weapon, explosives, and other dangerous items became very important problem for defending people against terrorist attacks. Recent time, many methods have been developed but number of methods are not efficient to effectively solve this problem. The main aim of the research in this work is devoted to the detection of concealed dangerous objects by increasing sensitivity and resolution in obtained images. In this paper, we propose to use inverse synthetic aperture radar (ISAR) technology for the detection of hidden items in the millimeterwave length. The millimeter-wave ISAR imaging of concealed cubes and a gun are studied. The theoretical background employed for the reconstruction of measurement results is briefly described. The millimeter-wave ISAR measurement setup is presented. Then, measurements carried out for different scenarios are explained. Finally, the reconstructed results are shown for all conducted measurements.

El-Cezeri Fen ve Mühendislik Dergisi, 2021

In this study, the suspended pendulum system was controlled by PID (Proportional-Integral-Derivat... more In this study, the suspended pendulum system was controlled by PID (Proportional-Integral-Derivative). Obtaining the system parameters was carried out using the PSO (Particle Swarm Optimization) algorithm in the simulation environment. For this purpose, the model of the suspended pendulum system's model was created. The parameters of the real system were found through the model. Viscous damping coefficient, Moment of Inertia and PID coefficients were calculated as parameters. The calculated values were used in the real system and the real system proved the accuracy of simulation the model. Control of the system was carried out in PLC (Programmable Logical Controller). The force required for the pendulum to reach a certain position was obtained by brushless motor control. ESC (Electronic Speed Control) is used as brushless motor driver and PWM (Pulse Width Modulation) is used as control signal of ESC. The encoder is used to measure the position of the system. System data was obtained with MATLAB. Communication between MATLAB and PLC is realized with OPC (OLE for Process Control). End of the study, it was observed that the simulation and optimization algorithm and the control of the real system gave similar results.

This paper presents a simple method for determining the dielectric constant of microwave PCB subs... more This paper presents a simple method for determining the dielectric constant of microwave PCB substrates. In the presented method, a bandpass microstrip filter on the PCB substrate with a user-predicted dielectric constant value is designed for a given center frequency, and it is implemented. The simulation results of the designed bandpass filter are obtained by the help of electromagnetic analysis software; XFDTD. Experimental results regarding the filter frequency characteristic are accomplished by means of a vector network analyzer. The simulation results of the designed filter are modified to overlap with the experimental ones by varying the dielectric constant value. When the simulation and experimental results are overlapped, the value of dielectric constant is accurately selected. In order to illustrate the validity of proposed method, the dielectric constant values of flame resistant-4 (FR4) substrates are acquired at IEEE 802.11b/g and IEEE 802.11a wireless local area networ...

In this study, an efficient and practical approach is proposed to increase the bandwidth of narro... more In this study, an efficient and practical approach is proposed to increase the bandwidth of narrow-band antennas by designing lossless impedance matching network with the simplified real frequency technique. Our algorithm does not require prior knowledge of network analytical topology of the load impedance that is to be matched. Any frequency-dependent data such as antenna radiation data (either measurement or simulated) can be easily matched via the proposed algorithm. The matching network realized by this technique is relatively simple and gives superior gain properties compared to that obtained by other methods. The proposed method is tested with various data sets for different antenna configurations. The results validate the effectiveness and the success of the algorithm.

2009 International Conference on Electrical and Electronics Engineering - ELECO 2009, 2009

In this paper, a method for obtaining focused inverse synthetic aperture radar (ISAR) images of t... more In this paper, a method for obtaining focused inverse synthetic aperture radar (ISAR) images of targets based on the radar backscattering measurements taken over wide bands and wide angles. The proposed method divides wide angle and wide frequency band into small aperture bands in the spatial frequency or Fourier domain. This set-up makes it possible to use fast calculation of ISAR images for every sub-aperture data set as in the case of standard ISAR case of small-bandwidth and small-angle. The details of the method are presented and numerical examples are given for the validation the method. The electromagnetic scattering estimation from the target is calculated via a hybrid simulator that uses both the physical optics and the shooting & bouncing ray concepts.

The Turkish Online Journal of Distance Education, 2012

In recent years, strategic planning has become one of the subjects that many institutions work on... more In recent years, strategic planning has become one of the subjects that many institutions work on to ensure the intuitions’ appropriate management based on realistic results. Therefore, this planning has to be taken into account and should provide planning direction on the bases of its results. Basically, the manager of strategic planning, leadership and strategic thinking and to act to help planners designed the tools, processes and concepts is a group. At the same time, the organization of the development and effective strategies will help to place. The purpose of this research is to provide SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis and to present new suggestions based on the opinions of students in the distance education system. In this work, we have applied Survey Method. The study group has consisted of 70 students and 11 instructors of Mersin Vocational School of Higher Education (MVSHE). All the data was surveyed during the spring semester of 2009. In t...

In this paper, a compact and effective implementation of physical theory of diffraction (PTD) for... more In this paper, a compact and effective implementation of physical theory of diffraction (PTD) formulation is proposed. The PTD formulation is tailored to recently developed high-frequency radar cross section (RCS) prediction tool; Predics. This PTD implementation is unique such a way that it is specially tailored to shooting and bouncing ray (SBR) technique via ray tracing and field tracing techniques. The detailed derivation of this PTD implementation is formulated and the algorithm steps are given together with its inclusion to Predics. The success and the validity of the proposed PTD implementation to the ray-launching RCS simulator have been tested with several benchmark targets that have either analytical or measured RCS values. Simulated RCS results ensure the accuracy of the proposed diffraction formulation that has been attached to the SBR technique over the test targets given within the paper. To better assess the effect of diffraction phenomenon to the total RCS value, mor...

IEEE Access, 2020

An assessment of polarimetric inverse synthetic aperture radar (Pol-ISAR) imaging is accomplished... more An assessment of polarimetric inverse synthetic aperture radar (Pol-ISAR) imaging is accomplished for realistic target models with the use of our recently developed high-frequency radar cross-section simulator tool called PREDICS. X-band, narrow-angle and full-polarimetric ISAR data for the CAD models of the well-known test object SLICY and a ground vehicle, namely a backhoe loader are analyzed to infer their structural characteristics. Experimental data obtained from a tower-turntable ISAR measurements of a T-72 tank target have also been utilized to assess the validity of the simulator. First, the intensity images in linear and circular polarization bases are directly utilized to evaluate the data quality and to characterize target features for classification. Then, the Pauli image decomposition scheme is applied to separate the basic scattering mechanisms occurring at target pixels. The identifiable canonical target forms are successfully extracted as single, double and multi-bounce scattering mechanisms that are pinpointed at their true locations. The results indicate that PREDICS is able to generate high-fidelity synthetic Pol-ISAR signatures of complex targets whereby successful interpretation of innumerous target scattering mechanisms and features can be achieved through Pauli decomposition scheme for classification purposes. INDEX TERMS PREDICS radar cross-section (RCS) simulator, inverse synthetic aperture radar (ISAR), Pauli decomposition, polarimetric ISAR.

International Journal of Engineering and Geosciences, 2021

In this study, a multithreaded method for triangular mesh three-dimensional computer aided design... more In this study, a multithreaded method for triangular mesh three-dimensional computer aided design objects is proposed to detect and extract wedges. Wedge detection is time consuming process for such objects that have large number of facets. To take the advantage of parallel computing opportunities, the algorithm is refactored in this study. Scope of variables, memory management and stack use are optimized for efficient use of computational resources. The proposed method is focused to calculation efficiency and performance on multicore / multithreaded processors and it is evaluated with benchmark, complex and realistic objects.

International Journal of Engineering and Geosciences, 2020

In this study, a quantitative radar cross section (RCS) analysis of different unmanned aerial veh... more In this study, a quantitative radar cross section (RCS) analysis of different unmanned aerial vehicle (UAV) models were accomplished by means of a series of RCS simulations. The simulations were carried out by high-frequency RCS simulation and analysis tool called PREDICS. To quantify the RCS features of the UAV model, both the anglevariation and frequency-variation simulations for all polarization excitations were performed. The results of the simulations suggested that RCS values were dramatically varying with respect to look angle with some special angles providing the large values of RCS. Generally, the RCS values of the UAV model was increasing with frequency as expected. A quantitative radar detection range analyses were also accomplished to assess the visibility of both the military-type and civil-type UAV models. The outcome of these studies has suggested that large-size UAV model can be easily detected by a high-sensitive radar on the ranges of tens of kilometers while thes...

International Journal of Engineering and Geosciences, 2020

Inverse synthetic aperture radar (ISAR) imaging is a reliable detection and classification techni... more Inverse synthetic aperture radar (ISAR) imaging is a reliable detection and classification technique for maneuvering targets at near and far-field ranges. In this study, we examine the near-field circular (turntable) ISAR imaging by conducting various real measurement experiments that were performed in the microwave anechoic chamber of the Mersin University’s MEATRC laboratory. The backscattered data were collected via a vector network analyzer that works as a Stepped Frequency Continuous Wave (SFCW) radar and for a number of simple and complex metal objects. The collected raw data were calibrated by using the backscattering data of a canonical object and then focused by applying a near-field backprojection image reconstruction algorithm. The resultant circular ISAR images demonstrate successful and well localized detection of various types of targets even though they are camouflaged by clothing. The obtained results reveal the preliminary efficacy of C band ISAR imaging in conceale...

International Journal of Engineering and Geosciences, 2021

Ground-based synthetic aperture radar (GB-SAR) systems are mostly utilized to be practical practi... more Ground-based synthetic aperture radar (GB-SAR) systems are mostly utilized to be practical practices in improved understanding of the complex mechanism of microwave backscattering. They also provide complementary information on evaluating the validity of the polarimetric analysis of air-borne or satellite-borne SAR applications. This study investigates some capabilities of polarimetric L-band GB-SAR imaging by testing its performance against a typical terrain and various kinds of manmade targets. Trihedral corner reflectors are also included in the analyses because of their importance in data calibration. Polarimetric backscattering signatures of different targets are analyzed in terms of qualitative assessment of amplitude images and identification and classification of scattering mechanisms through target decomposition techniques. The findings of these analyses and detailed discussions are presented. Specifically, the entropy/mean-alpha ((H/α ̅)) classification results are shown t...

Journal of Electrical and Computer Engineering, 2017

An algorithm for detecting cavities inside a tree-body is presented with simulation and measured ... more An algorithm for detecting cavities inside a tree-body is presented with simulation and measured examples. The details of the imaging algorithm that is based on sinusoidal template focusing routine are given. First, the algorithm is tested with the simulation scenario for which perfect reconstruction of the simulated cavity structure together with tree-body is successfully formed in MATLAB programming environment. Then, the algorithm is applied to the measurement data that have been collected from a laboratory set-up. Collected backscattered measurements from the tree-body (with cavity) structure are used to generate the image of the scene by the help of our proposed algorithm. The resultant radar images of the measured data collected from the laboratory arrangement have shown the applicability of the developed algorithm for the detection of cavity structures inside tree-bodies.

Progress In Electromagnetics Research M, 2018

In this study, the scattering map of the breast is reconstructed by applying the matchingpursuit ... more In this study, the scattering map of the breast is reconstructed by applying the matchingpursuit algorithm (MPA) to the simulation data obtained by the monostatic inverse synthetic aperture radar (ISAR) principle, and the locations of the tumors are determined by considering the peaks on the scattering map. The MPA iteratively searches the true solution by assuming every discrete point in the solution space to be a scattering center by dividing the imaging region onto a discrete grid. In order to obtain images with better resolution, the fine granularity of the grid for accurate solutions is provided at the expense of increased processing times. First, our approach based on MPA is tested on simulated data generated by MATLAB for breast tumor detection and imaging. Perfect reconstruction for the locations of the hypothetical breast tumor points is attained. Then, a full-wave electromagnetic simulation software named CST Microwave Studio (CST MWS) is used to generate backscattered electric field data from a constructed scenario in which a tumor is located in a breast model. Next, we use the collected data from the defined scenarios as an input to our algorithm. Resultant images provide successful detection and imaging of the tumor region within the breast model. The accuracy of the MATLAB and the CST MWS simulation results demonstrate the availability of our MPA-based focusing algorithm to be used effectively in medical imaging.

Turkish Journal of Engineering, 2017

In this paper, we propose an ultrawide band design for the double ridged horn (DRH) antenna to be... more In this paper, we propose an ultrawide band design for the double ridged horn (DRH) antenna to be used behind the obstacle radar (BOR) applications such as ground penetrating radar (GPR) and through the wall radar (TWR) imaging. The design is developed and optimized by the help of full electromagnetic simulator code; CST. The design parameters such as frequencies of operation and the half power beam width (HPBW) are taken into account by considering the BOR application requirements. The design double ridged horn antenna provides a frequency bandwidth between 1.5 GHz and 7 GHz and HPBW around 30° around the center frequency that are very suitable for GPR and TWR applications. The final optimized design that is formed by CST is physically manufactured and measured. The prototyped DRH antenna’s measurement antenna parameter results are in good agreement with the simulated ones.

Progress In Electromagnetics Research B, 2008

It is well known in B-scan ground penetrating radar (GPR) imagery that the underground scatterers... more It is well known in B-scan ground penetrating radar (GPR) imagery that the underground scatterers generally exhibit defocused, hyperbolic characteristics. This is mainly due to the data collection scheme and the finite beam width of the main lobe of the GPR antenna. To invert this undesirable effect and obtain focused images, various migration or focusing algorithms have been developed. In this paper, we survey the performance of our recent focusing algorithms, namely; hyperbolic summation (HS) and frequency-wavenumber (w-k) based synthetic aperture radar (SAR) focusing. The practical usage of these focusing methods were tested and examined on both simulated and measured GPR data of various buried targets. The simulation data set is obtained by a physical optics shooting and bouncing ray (PO-SBR) technique code. Measurements were taken by a stepped frequency continuous wave (SFCW) radar setup. Scattered C-band field data were measured from a laboratory sand box and from outdoor soil environment. The proposed focusing methods were then applied to the B-scan GPR images to enhance the resolution quality within these images. The resultant GPR images obtained with the proposed algorithms demonstrate enhanced lateral resolutions.

The capacity of forward link (FL) communication to mobile receivers is limited primarily by co-ch... more The capacity of forward link (FL) communication to mobile receivers is limited primarily by co-channel interference (CCI). Adaptive Antenna Arrays (AAAs) that employ antenna arrays along with advanced signal processing at the base station (BS) have been proposed to mitigate this limitation. We present FL capacity analysis for mixed voice and data user traffic scenarios in third generation (3G) CDMA cellular network, where each BS is equipped with either three-sector uniform linear array (ULA) or non-sectorized uniform circular array (UCA). We demonstrate that the FL capacity of the system is considerably affected by the antenna array topology. We find that the optimum element spacing resulting in the largest FL system capacity is 0,5 for both ULA and UCA topologies. Also, it is found that the UCA provides larger FL capacity when compared to the ULA under the same array parameters, i.e., element spacing and number of elements per cell.

In this work, several cancellation techniques for undesired clutter in various SAR images are pre... more In this work, several cancellation techniques for undesired clutter in various SAR images are presented. As a good example of SAR imagery, publicly released MSTAR images are taken as the practical application. The modelling of clutter is done by probabilistic approach. Target detection techniques including CFAR (Constant False Alarm Rate) is applied. To find the best fit for the background clutter, higher-order statistics are implemented and various distributions from Rayleigh to Weibull are tested. By using adaptive threshold CFAR detectors MSTAR targets are effectively segmented from clutter backgrounds.

A comparativestudy on the performance of the computational electromagnetic methods (CEMs) namely ... more A comparativestudy on the performance of the computational electromagnetic methods (CEMs) namely finite difference time domain (FDTD), finite element method (FEM) and moment method (MoM) via their corresponding electromagnetic softwarehas been presented forC, E, H and Lshaped compact microstrip antennas (CMAs)constructed by slot-loading the rectangular patch. For this purpose, the antennas were simulated with the use of CEMs and fabricated by using Rogers RT/duroid 5870 materials. The simulations were then compared with the measurements with respect to the return loss curves (s 11). The comparative results have been presented to illustrate the conformity rate between the simulations and measurement in term of the resonant frequency of 10-dB bandwidth.

2011 XXXth URSI General Assembly and Scientific Symposium, 2011

The detection of concealed objects like weapon, explosives, and other dangerous items became very... more The detection of concealed objects like weapon, explosives, and other dangerous items became very important problem for defending people against terrorist attacks. Recent time, many methods have been developed but number of methods are not efficient to effectively solve this problem. The main aim of the research in this work is devoted to the detection of concealed dangerous objects by increasing sensitivity and resolution in obtained images. In this paper, we propose to use inverse synthetic aperture radar (ISAR) technology for the detection of hidden items in the millimeterwave length. The millimeter-wave ISAR imaging of concealed cubes and a gun are studied. The theoretical background employed for the reconstruction of measurement results is briefly described. The millimeter-wave ISAR measurement setup is presented. Then, measurements carried out for different scenarios are explained. Finally, the reconstructed results are shown for all conducted measurements.