Elektrik - Elektronik Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12469/47

Browse

Now showing 1 - 9 of 9

Analytic Solution of the Feldtkeller Equation
(Elsevier GMBH Urban & Fischer Verlag, 2009) Şengül, Metin Y.
In every reflectance-based application like broadband matching circuit modeling etc. a nonlinear equation following from energy conservation the Feldtkeller equation must be solved in order to obtain real networks. In the literature however there is no analytic solution available but only numerical solutions. Consequently the resulting error depends on the accuracy of the numerical tools. In this paper an analytic solution is proposed which is based on the modified ABCD-parameters of a lossless reciprocal two-port network. An algorithm is presented and examples are included to illustrate the implementation of the analytical method. (C) 2008 Elsevier GmbH. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 4
Broadband Impedance Matching Via Lossless Unsymmetrical Lattice Networks
(Elsevier GMBH Urban & Fischer Verlag, 2012) Şengül, Metin Y.
In this paper a broadband impedance matching network (equalizer) design algorithm has been proposed. In the equalizer a lossless unsymmetrical lattice network has been utilized. The branch impedances of the lattice network are considered as singly terminated lossless LC networks since it is not desired to dissipate power in the equalizer. After giving the algorithm its usage has been illustrated via an example. (C) 2011 Elsevier GmbH. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 4
Design of Broadband Microwave Amplifiers With Mixed-Elements Via Reflectance Data Modeling
(Elsevier GMBH Urban & Fischer Verlag, 2008) Şengül, Metin Y.; Yarman, Sıddık Binboğa
A practical method is introduced to design single-stage broadband microwave amplifiers with mixed lumped and distributed elements via modeling the reflectance data obtained from lumped-element input and output matching network prototypes. The same transducer power gain level is obtained by using less number of lumped-elements in the mixed-element amplifier than that of the lumped-element amplifier prototype. A mixed-element amplifier design is presented to exhibit the utilization of the method. It is expected that the method will be employed to design microwave amplifiers for broadband communication systems. (C) 2007 Elsevier GmbH. All rights reserved.
Citation - WoS: 6
Citation - Scopus: 8
Design of Broadband Single Matching Networks
(Elsevier GMBH Urban & Fischer Verlag, 2009) Şengül, Metin Y.
In general commercially available software tools are preferred to design broadband matching networks for wireless communication systems. But they need a properly selected matching network topology with good initial element values. Therefore in this paper a new real frequency technique is presented to generate broadband single matching networks with suitable initial element values. In the proposed method load impedance is written in terms of ABCD-parameters of the desired matching network and the source resistor. Then free parameters are optimized which in turn yields the desired matching network with initial element values. It is not needed to select a circuit topology for the matching network which is the natural consequence of the matching processes. Also there is no need to select the desired transducer power gain level , the proposed technique naturally provides a gain curve fluctuating around the final available level. Eventually the initial design is improved by optimizing the performance of the matched system employing the commercially available computer-aided design (CAD) packages. An algorithm and two examples are given to illustrate the utilization of the proposed technique. (C) 2007 Elsevier GmbH. All rights reserved.
Citation - WoS: 11
Design of Distributed-Element Rf Filters Via Reflectance Data Modeling
(Elsevier GMBH Urban & Fischer Verlag, 2008) Şengül, Metin Y.; Yarman, Sıddık Binboğa; Volmer, Christian; Hein, Matthias A.
A reflectance-based modeling method is presented to obtain the distributed-element counterpart of a lumped-element network which is described by measured or computed reflectance data at a set of frequencies. Numerical generation of the scattering parameters forms the basis of this modeling tool. It is not necessary to select a circuit topology for the distributed-element model which is the natural consequence of the modeling process. Our approach supplements the known interpolation methods by a simple technique that does not involve complicated cascaded circuit topologies and whose numerical convergence is proven. To illustrate the utilization of the proposed method a lumped-element low-pass Chebyshev filter is transformed to its distributed-element counterpart. The filter designed for a frequency band around 1 GHz was fabricated and experimentally characterized. We find excellent agreement between measured and simulated transducer power gain over the entire frequency band. (c) 2007 Elsevier GmbH. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 5
Design of Practical Broadband Matching Networks With Commensurate Transmission Lines
(Elsevier GMBH Urban & Fischer Verlag, 2013) Şengül, Metin Y.
To design broadband matching networks for microwave communication systems commercially available computer aided design (CAD) tools are always preferred. But these tools need proper matching network topology and element values. Therefore in this paper a practical method is proposed to generate distributed-element matching networks with good initial element values. Then the gain performance of the designed matching network can be optimized employing these tools. The utilization of the proposed method is illustrated by means of the given example. It is shown that proposed method provides very good initials for CAD tools. (C) 2013 Elsevier GmbH. All rights reserved.
Citation - WoS: 7
Citation - Scopus: 9
Detection of Interdependent Primary Systems Using Wideband Cognitive Radios
(Elsevier GMBH Urban & Fischer Verlag, 2013) Yılmaz, Burak; Erküçük, Serhat
Cognitive radios (CRs) may be sharing multiple frequency bands with primary systems if the CR is a wideband or an ultra wideband (UWB) system. In that case the CR should ensure all the coexisting primary systems in these bands are detected before it can start data transmission. In this work we study the primary system detection performance of a wideband CR assuming that there are multiple coexisting primary systems and that these primary systems may be jointly active. Accordingly we consider the implementation of energy detection scheme in multiple bands followed by two detection methods: (i) a maximum-a-posteriori (MAP) based detection (i.e. joint detection) that takes into account the statistics of simultaneously operating systems in independent bands and (ii) a Neyman-Pearson (NP) test based detection that optimizes the threshold values independently in each band (i.e. independent detection). For a simpler implementation of the independent detection we show that the threshold values obtained from joint detection can be used in order to achieve the optimum NP test based independent detection results. In addition to quantifying the gain of joint detection over independent detection in terms of probabilities of false alarm and detection for practical scenarios we also present the operation capability of CRs in terms of the fractions of time the CR can access the channel without interfering with the primary systems. The results are important for the practical implementation of multiband detection when the primary systems are known to be interdependent. (C) 2013 Elsevier GmbH. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 3
Linear Expansions for Frequency Selective Channels in Ofdm
(Elsevier GMBH Urban & Fischer Verlag, 2006) Şenol, Hande; Çırpan, Hakan Ali; Panayırcı, Erdal
Modeling the frequency selective fading channels as random processes we employ a linear expansion based on the Karhumen-Loeve (KL) series representation involving a complete set of orthogonal deterministic vectors with a corresponding uncorrelated random coefficients. Focusing on OFDM transmissions through frequency selective fading this paper pursues a computationally efficient pilot-aided linear minimum mean square error (MMSE) uncorrelated KL series expansion coefficients estimation algorithm. Based on such an expansion no matrix inversion is required in the proposed MMSE estimator. Moreover truncation in the linear expansion of channel is achieved by exploiting the optimal truncation property of the KL expansion resulting in a smaller computational load on the estimation algorithm. The performance of the proposed approach is studied through analytical and experimental results. We first exploit the performance of the MMSE channel estimator based on the evaluation of minimum Bayesian MSE. We also provide performance analysis results studying the influence of the effect of SNR and correlation mismatch on the estimator performance. Simulation results confirm our theoretical results and illustrate that the proposed algorithm is capable of tracking fast fading and improving performance. (c) 2005 Elsevier GmbH. All rights reserved.
Citation - WoS: 6
Citation - Scopus: 7
Modeling Based Real Frequency Technique
(Elsevier GMBH Urban & Fischer Verlag, 2008) Şengül, Metin Y.
Usually commercially available software tools are used to design matching networks for wireless communication systems. But a properly selected matching network topology with good initial element values must be supplied to these tools. Therefore in this paper a modeling-based real frequency technique (M-RFT) is presented to generate matching networks with initial element values. In the proposed method output impedance data of the matching network are obtained in terms of ABCD-parameters of the load model. Then they are modeled which in turn yields the desired matching network with initial element values. It is not needed to select a circuit topology for the matching network which is the natural consequence of the matching processes. Also there is no need to select the desired transducer power gain level

Browse

Browsing Elektrik - Elektronik Mühendisliği Bölümü Koleksiyonu by Publisher "Elsevier GMBH Urban & Fischer Verlag"