Mesut Kartal

A NEW TRIPLE BAND CIRCULARLY POLARIZED SQUARE SLOT ANTENNA DESIGN WITH CROOKED T AND F-SHAPE STRIPS FOR WIRELESS APPLICATIONS

A new design for circularly polarized square slot antenna (CPSSA) is presented. The circular polarization operation in the proposed single-layer antenna is created through two equal sized crooked T-shape and an F-shape strips located on the patch. Compared to most of the previously reported CPSSA structures, the impedance bandwidth and the axial ratio bandwidth of the antenna are increased and also the size of the antenna becomes smaller. The presented CPSSA design has the compact dimensions of 40 £ 40 £ 0:8mm 3 , total impedance matching bandwidth of 8.04GHz and exhibiting a 28.03% (4.6{6.1GHz) 3dB axial ratio bandwidth. A prototype of the antenna is fabricated and tested, and a great agreement with simulated results is obtained.

Efficient Strip-Mode SAR Raw-Data Simulation of Fixed and Moving Targets

The performance of the high-resolution synthetic aperture radar (SAR) with moving-target indication and imaging systems can be analyzed and evaluated by modeling the whole imaging system through a simulation. The raw-data generation in the time domain achieves a realistic simulation procedure provided that computational complexity can be tolerable. In this letter, we proposed an efficient SAR raw-data generator of a scene that includes both static and moving targets. The raw data set of an extended scene and the moving target is simulated in the frequency domain separately and superposed in the time domain. The generated raw data for fixed and moving targets are also processed and analyzed.

Efficient Stripmap-Mode SAR Raw Data Simulation Including Platform Angular Deviations

The radiometric performance of high-resolution synthetic aperture radar systems under degrading conditions such as the unintentional angular motion of the platform can only be analyzed and evaluated by modeling the whole imaging system through simulation. The raw data generation in the time domain achieves a realistic simulation procedure but, on the contrary, is time inefficient. The frequency-domain approach promises computational efficiency; however, it lacks the consideration of the antenna deviations. In this letter, we propose a frequency-domain stripmap-mode raw data generator of an extended scene, taking into consideration the platform angular deviations. The generated raw data are also validated, and the corresponding radiometric degradation is analyzed.

Time domain SAR raw data simulation of distributed targets

In this paper, a time domain stripmap mode Synthetic Aperture Radar (SAR) raw data simulation including both the terrain and the targets is proposed. The simulator generates SAR raw data of a scene, involving both single and double reflections in a computationally efficient manner. The inputs of the simulator are the digital elevation model of the terrain, the 3D target model, and the parameters of the SAR system. The simulator extracts a geometrically accurate reflectivity map and generates the SAR raw data in time domain. The disadvantage of time domain method is justified to be tolerable by presenting experiments on modularity performance of the simulator. Also a novel method to decrease the time domain computational complexity of the SAR raw data generation is proposed. Our method has showed very promising results in representing the scattering characteristics, the raw data, and the time domain simulation flexibility.

Compact and Broadband 4

A novel two-layer 4 × 4 Butler matrix by feeding substrate integrated waveguide is designed and realized. The proposed Butler matrix has broadband operation frequency range of over 8.5 to 10.6 GHz with excellent phase and amplitude performance. The proposed design in this letter prevents the loss of amplitude and phase shifts in Butler matrix and decreases amplitude imbalance to less than 0.6 dB. This is achieved by reducing the size of Butler matrix and avoiding the use of a line length which causes a phase shift.

\times

In this study, the support vector machine (SVM) was used as a classifier to identify aerospace objects. Radar target identification based on high resolution range profiles (HRRPs) received much attention because of its reduced complexity than those using two-dimensional (2-D) ISAR images. Therefore range profiles were used as feature vectors to represent radar data. Data sets which are for training and testing were generated by using a program called radar target backscattering simulation (RTBS) for three different target types. The performance of the SVM was compared with other classification algorithms including statistical classification techniques such as maximum likelihood (ML) and fisher linear likelihood (FLL).

4 SIW Butler Matrix With Phase and Magnitude Error Reduction

The penetration of microwaves in various materials gives active microwave imaging a large potential for some applications in medical imaging. This fairly recent imaging technique is aimed at obtaining some information about the physical properties of an object which is exposed to low power incident microwave radiation. Measured external scattered field data is used for the imaging purpose. In this computer simulation work, electromagnetic far field scattered data of a dielectric cylinder having infinite length are used for reconstruction under Born approximation. Using a series of integral transform, the three fold Radon transform integral is reduced into one fold. Having found the Radon transform of the object function, inverse Radon transform algorithms are used to reconstruct it. These three different inverse Radon transform methods are direct inverse Radon transform, convolution back projection and filter back projection. The result of the computer simulation algorithms of different methods are presented.<<ETX>>

Radar target classification based on support vector machines and High Resolution Range Profiles

A multistage parallel algorithm with iterative processing is discussed for the processing of information in diffraction tomography. The algorithm is based on matrix partitioning, which results in mostly parallel stages of processing. Each successive stage is designed to minimize the remaining error. The process is iterated until convergence. The major advantages of the multistage algorithm are the reduced computational time from faster convergence as compared with a single-stage iterative algorithm, further reduction of computation time if the stages are implemented mostly in parallel, and better performance in terms of reduced reconstruction error.

Image reconstruction with diffraction tomography using different inverse Radon transform algorithms

This work is proposed to design shielding for interference mitigation and network security within the buildings in the unlicensed 2.4GHz ISM band and to provide maximum transparency at broadcast frequencies. Thus, mobile phones, radio and television signals in buildings will not be affected. Frequency Selective Surface (FSS) is attached onto existing common construction material to transform the standard material into a band stop frequency selective wall. To obtain the band response of FSS having a desired frequency interval, a new FSS periodic element geometry is introduced. The obtained results show that desired frequency response is achieved. HFSS software is used for simulation purposes.

Multistage parallel algorithm for diffraction tomography.

A New Point Scatterer Prediction Model is presented in this paper to predict RCS of an aircraft model using Inverse Synthetic Aperture Radar (ISAR) images of the aircraft.. The ISAR images are provided by Defense Agency of Sweden and Saab inc. for each 15 degrees in horizontal plane. RCS is predicted for each aspect angle by taking superposition of the dominant point scatterers whose locations and strength are calculated from these ISAR images and simulation results are given with measurement results of the same aircraft model.