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Yayın A tunable inductance topology to realize frequency tunable matching networks and amplifiers(IEEE, 2013) Atilla, Doğu Çağdaş; Aydın, Çağatay; Köprü, Ramazan; Nesimoğlu, Tayfun; Yarman, Bekir Sıddık BinboğaCoverage of commercial communication standards such as GSM, UMTS, Wi-Fi and Wi-Max within a single transceiver chip is one of the most desired properties by wireless communication manufacturers. In this regard, communication companies are keenly interested in the design of high power amplifiers for broadband cellular communications to achieve this coverage. In this work, design of broadband tunable matching networks is investigated using Real Frequency Techniques. In practical applications, tunability is needed to compensate for the load impedance variations with environmental effects. In order to be able to work on sample structures, impedance transforming filters with proper topology are chosen and a broadband tunable matching network with a tunability strategy is developed. Eventually a broadband amplifier has been designed using the tunable inductor concept.Yayın Image recovery of inaccessible rough surfaces profiles having impedance boundary condition(IEEE, 2022) Sefer, Ahmet; Yapar, AliThis letter addresses a reconstruction algorithm of locally rough inaccessible surface profiles via the knowledge of the scattered field data under the consideration of the impedance boundary condition (IBC). To this aim, first, the synthetic scattered field data are obtained through the solution of the conventional surface integral equation (SIE) written on the rough surface. Then, the same SIE together with the data equation is solved iteratively via Newton's method to obtain the image of the rough surface profile. In the numerical implementation, the nonlinear ill-posed inverse problem is linearized in an iterative fashion via the Newton method and regularized by Tikhonov in the least-squares sense. The feasibility of the algorithm is provided via numerical examples, which shows that the method is effective and promising.Yayın A broadband microwave amplifier design by means of immittance based data modelling tool(IEEE, 2002) Kılınç, Ali; Pınarbaşı, Hacı; Şengül, Metin; Yarman, Bekir Sıddık BinboğaIn this paper a practical broadband microwave amplifier design algorithm is introduced utilizing the immittance data-modelling tool. In the course of design, first, the optimum input and output terminations for the active device are produced employing the real frequency technique. Then, these terminations are modelled utilizing the new immittance-modelling tool to synthesize the front-end and back-end matching networks. An example is included to exhibit the implementation of the proposed design algorithm to construct a single stage BJT amplifier over a wide frequency band. It is expected that the proposed design algorithm will find applications to realize wideband microwave amplifiers put on MMIC for mobile communication.Yayın Dual band filter design for GSM bands using frequency mapping and real frequency technique(IEEE, 2018) Yıldız, Serkan; Kılınç, Sedat; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaIn this study, dual band frequency mapping is incorporated with Real Frequency Technique to design a dual band filter for GSM900 and GSM1800/UMTS bands. The proposed real frequency design technique (RFT) involves a parametric representation of input impedance of filter and the use of a dual band (DB) frequency mapping. A direct DB frequency mapping from low pass proto-type network is utilized along with the design and optimization of a low pass prototype network. Microstrip implementation of the designed filter and measurement results of the design are presented.Yayın A parametric approach to construct two-variable positive real impedance functions for the real frequency design of mixed lumped-distributed matching networks(IEEE, 2004) Aksen, Ahmet; Pınarbaşı, Hacı; Yarman, Bekir Sıddık BinboğaIn this paper, a parametric approach to construct two-variable positive real driving point impedance functions characterizing lossless ladder networks with mixed lumped and distributed elements is presented. The proposed approach is based on the generation of two-variable positive real impedance functions from the single variable boundary conditions. Utilizing the proposed parametric construction algorithm, real frequency matching technique is extended to the design of matching networks with mixed lumped and distributed elements. The application of the approach is illustrated by a broadband microwave amplifier design incorporating mixed lumped and distributed type matching networks. The resultant design has been compared with the AWR Microwave Office software simulation.Yayın A method for low-pass filter designing by commensurate transmission lines(IEEE, 2016) Momen, Hadi Ghasemzadeh; Köprü, RamazanIt is well known that the complex Richards-Plane is a transformed domain of Laplace-Plane which is obtained under a tangent hyperbolic mapping. Network functions generated in terms of Richards's frequency are periodic in actual frequencies with periodicity of pi. Once a low-pass prototype network function is designed in Richards's domain, then its periodic feature makes the corresponding periodic band-pass network function to appear at the certain bands repetitively in the frequency axis. Depend on the application requirements, designer can choose the interested band among these repetitive bands. In this work, a filter is built with microstrip commensurate transmission lines in GSM operation pass-band (0.8 <= f <= 2.4 GHz) . This network can be used in communication applications which are designed to operate in the range of GHz as well as the application in a microstrip patch antenna. In the proposed design, Simplified Real Frequency Technique (SRFT) is employed in the frequency detection network, and the simulation result of microwave office tool (AWR) confirms the theoretical result obtained by MATLAB.Yayın RFT Based multiband matching network design with foster resonance sections(IEEE, 2015) Yıldız, Serkan; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaA new method for a multi band matching network design is introduced in this paper. Foster resonance sections are used to create transmission zeros. This effect brings gain degradation at Transducer Power Gain (TPG) of the matching circuit at assigned frequencies of resonance sections. Single matching problem is concerned. It has been shown that proposed method gives good control on creating multiband characteristics.Yayın A lumped circuit model for the radiation impedance of a 2D CMUT array element(IEEE, 2005) Bozkurt, Ayhan; Karaman, MustafaElements of a 2D array used for 3D acoustic imaging have dimensions smaller than half of the acoustic wavelength due to the Nyquist criteria for spatial sampling. Therefore, analyses involving circuit models for the array elements have to account for the reactive part of the radiation impedance of the array element. In this paper, we introduce a lumped circuit model for the complex radiation impedance of a 2D CMUT array element. Using the finite element method (FEM) we first show that the radiation impedance of the array element is identical to that of a plane piston transducer of comparable dimensions. Then, we show that the complex radiation impedance of the 2D array element can be represented by a simple resonant circuit placed parallel to the real radiation impedance in the Mason's equivalent circuit. The component values of the reactive lumped elements forming the resonant circuit were determined by fitting the impedance of overall equivalent circuit to the FEM results using the Nelder-Mead minimization algorithm.Yayın Real frequency design of multiband matching networks with mixed lumped-distributed elements and foster resonance sections(IEEE, 2018) Yıldız, Serkan; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaIn this study, a multiband matching network design technique is presented. Mixed lumped and distributed elements are used to form Transducer Power Gain (TPG) of the matching network. Finite frequency transmission zeros are included in final design to create multiband TPG characteristic. Foster resonance sections are used to realize finite transmission zeros. Approximate distributed model of Foster resonance section is incorporated in design. An illustrative dual band matching network design for a PIFA antenna is presented. It has been shown that using distributed equivalent models of Foster resonance sections in mixed matching network design provides satisfactory TPG levels at intended frequency bands.Yayın Microwave amplifier design for mobile communication via immittance data modelling(IEEE, 2003) Kılınç, Ali; Pınarbaşı, Hacı; Yarman, Bekir Sıddık Binboğa; Aksen, AhmetIn this paper, a practical broadband microwave amplifier design algorithm based on immittance data modelling is presented. In the course of design, first, the optimum input and output terminations for the active device are produced employing the real frequency technique. Then, these terminations are modelled utilizing the new immittance-modeling tool to synthesize the front-end and back-end matching networks. An example is included to exhibit the implementation of the proposed design algorithm to construct a single stage wideband microwave amplifier over a wide frequency band. It is expected that the proposed design algorithm will find applications in the design of microwave amplifiers put on MMIC for mobile communication.
