فهرست مطالب

Majlesi Journal of Telecommunication Devices
Volume:7 Issue: 1, Mar 2018

  • تاریخ انتشار: 1397/01/20
  • تعداد عناوین: 6
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  • Emine AvŞ, Ar Aydin Pages 1-4
    Subsurface scanning problems, which both it is one of microwave imaging techniques and there are applications in various fields, has become a very interesting topic today. Many methods have been developed to detect cancer cells. The electrical properties of malignant cancer cells compared to normal cells indicate significant differences at microwave frequencies. Since breast tissue according to such as brain and muscle tissues is permeable than these tissues, this case supports the idea of imaging of cancerous cells in the microwave range. Various techniques such as mammography for breast cancer diagnosis are inadequate in detecting malignant cells, have high cost, and also patients are exposed harmful rays. Because of these, it is not a desirable situation. Therefore, non-ionizing electromagnetic waves used to detect cancerous cells in the human body has been widely used in biomedical applications nowadays. In this paper, both an antipodal Vivaldi antenna with enhanced bandwidth and a 3D breast structure which has different permittivity and conductivity is modelled in CST software simulation tool to solve electromagnetic field values. Return loss, VSWR, and radiation pattern characteristics which are significant antenna parameters are simulated and obtained whether the antenna possess an efficient characteristic or not. Also, electric field values over the breast tissue with tumor and without tumor are evaluated.
    Keywords: antipodal Vivaldi antenna, breast cancer, computer simulation technology (CST), dielectric properties
  • Duygu Nazan GenÇoĞ, Lan, Ş, Ule, Ccedil, Olak Pages 5-9
    Beveled edge rounded bowtie antenna is proposed for UWB applications in this paper. Beveling technique is employed to increase the bandwidth of classical bowtie antenna. The simulated bandwidth is from 3 GHz to 11 GHz in order to observe the bandwidth enhancement in the frequency range of interest for UWB applications. Effective parameters of the antenna, including Return Loss (S11), Voltage Standing Wave Ratio (VSWR) and radiation pattern are examined for the proposed structure. Then behavior of the designed antenna is compared with the classical bowtie antenna and rounded bowtie antenna characteristics to verify the enhancement due to the beveled edge structure. Besides, it is demonstrated that the proposed antenna satisfies UWB requirements by providing return loss less than -10 dB and VSWR less than 2, respectively during the enhancement process. Beveled edge rounded bowtie antenna model is designed by using CST Microwave Studio Program which is an electromagnetic simulation auxiliary tool.
    Keywords: Antenna Design, Beveling Technique, Bowtie Antenna, CST Microwave Studio, Ultra-Wideband
  • Gokcen Ozdemir Ozdemir, Murat Emre Erkoc, Nurhan Karaboga Pages 11-15
    In this study, 16-channel cosine modulated filter bank is designed. In the proposed design, the coefficients of the prototype low-pass Finite Impulse Response filter with an N=64 filter order is optimized using Artificial Bee Colony Algorithm. In the presented study, different design examples are given with different frequency band values. Amplitude response error and transition band error values are obtained for each design examples. Via these examples, the effects of the change in transition and stopband frequencies on the performance of the designed filter bank is investigated. Simulation results show that determining frequency band values of prototype filter properly improves the performance of the filter bank and decreases the amplitude response error and transition band error values.
    Keywords: ABC Algorithm, cosine modulated filter bank, pass-band frequency, stop-band frequency
  • Murat Emre Erkoc, Gokcen Ozdemir, Nurhan Karaboga Pages 17-21
    Compressive sensing is a technique that can reconstruct sparse signals under Nyquist rate. This study is about comparison of widely used sparse signal reconstruction algorithms under noisy measurements. Three algorithms, Orthogonal Matching Pursuit, Compressive Sensing Matching Pursuit and Primal Dual Interior Point method are used to reconstruct sparse signal from noisy measurement and performance results are compared. Firstly, a sparse signal is sampled under Nyquist rate and observation vector is obtained. After that, white Gaussian noise is added to this observation vector. Then, sparse reconstruction algorithms are employed to reconstruct the original signal from noisy measurement. These algorithms are tested for various measurement number and sparsity levels. Test conditions are same for all algorithms. Finally some performance metrics results related to reconstructed signal are obtained. These performance metrics are mean squared error, correlation of the reconstructed signal and original signal, reconstruction time of the algorithms and iteration numbers. According to these metrics, when sparsity level is very smaller than measurement number, Orthogonal Matching Pursuit has better results than others. However, when sparsity level is increased and close to measurement number, Primal Dual Interior Point method has better performance than others in terms of reconstruction a sparse signal from noisy measurement.
    Keywords: Compressed sensing, greedy algorithms, l1 minimization, sparse signal reconstruction
  • Servet K., Ouml, Ni, Halil Erol Pages 23-26
    In the communication sector, a large amount of data needs to be transmitted very quickly with an increasing user demand. To accommodate these demands, single carrier systems leave their place to multiple carrier systems. The transmission of large amounts of data at high speed requires high-quality radio access over multi-way damped channels. The amplitudes of the signals reaching the receiver at different times and paths are caused by fluctuations in the signal strength, this is called damping effect. The received signal is weaker than the transmitted signal due to the average transmission loss and damping. The adverse effects such as the damping effect on the communication channel greatly affect the performance of the wireless communication and prevent to reach high transmission speeds. In addition to multipath demodulation, multipath propagation also extends the time required for the transmitted signal to reach the receiver. In wireless communication systems, the best way to mitigate the damping effect on the channel is to take advantage of diversification techniques. OFDM, one of the multi-carrier systems, provides efficient channel capacity enhancement. In this study, the performances of least squares (LS) and minimum mean square error (MMSE) estimation methods, which are channel estimation methods, required to remove the interchannel interference in the OFDM technique are investigated by computer simulations. In interchannel interference in the OFDM technique is analyzed with LS and MMS estimation methods and results are compared with respect to Signal to Noise Ratio aspect. The results are promising.
    Keywords: Orthogonal frequency division multiplexing(OFDM), Multi input multi output (MIMO), Least Square (LS), Minimum Mean-Square Error (MMSE)
  • Cem. Ati, Lgan, Kazi, M. Zengin, Muammer UĞ, Ur, Evren, Ccedil, AĞ, Larer Pages 27-32
    In today's world, the usage area of intelligent systems is increasing day by day. With the development of technology, applications on intelligent systems that will facilitate human life have also gained momentum. Intelligent systems have evolved from the automotive to the defense industry, from white goods to construction. In large areas with high circulation such as large shopping malls, airports, train stations and stadiums, whose numbers are rapidly increasing, there is a problem of parking space and finding parking space in these areas. Due to the large number of car parks and the large number of vehicles, it is time consuming for customers to search for parking lots for a minute. It is also indisputable that the loss of time is the cause of money loss. In this study, it is aimed to provide a dynamic and quick solution to the operation of intelligent systems in the parking lot. By combining software, control, and sensor technologies, an intelligent system that continually updates itself and at the same time minimizes the loss of life and property in an emergency is designed and integrated into the parking lot infrastructure. Thanks to the designed system, it is aimed to get rid of the problem of searching for places, to reduce fuel and time loss the most, to protect from accidents, and to provide healthy guidance in possible emergency situations. Unlike similar projects in this study, the parking lot plan was created in software environment with all lines. Since the system is constantly updating itself, it has achieved an autonomous structure. In this way, the system does not need to enter any human being in the right direction at the shortest time.
    Keywords: Smart Systems, Control, Automation, Software, Sensor Technology, Arduino