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Yayın On numerical design technique of wideband microwave amplifiers based on GaN small-signal device model(Springer, 2014-10) Köprü, Ramazan; Kuntman, Hulusi Hakan; Yarman, Bekir Sıddık BinboğaThis work presents an application of Normalized Gain Function (NGF) method to the design of linear wideband microwave amplifiers based on small-signal model of a device. NGF has been originally developed to be used together with an S-parameter (*.s2p) file, whereas this work enables the NGF to be able to work with explicit S-parameter formulae derived from the small-signal model of the device. This approach provides the designer to be able to use simple set of S-parameter equations instead of S-parameter file of the device. Representation of the device simply by several model equations not only eliminates the need of carrying large number of data but also provides the capability of equation-based easy, realistic and equispaced S-parameter data generation in any desired resolution in frequency axis without requiring interpolation. NGF is defined as the ratio of T and |S-21|(2), i.e. T-N = T/|S-21|(2), gain function of the amplifier to be designed and transistor forward gain function, respectively. Synthesis of output/input matching networks (OMN/IMN) of the amplifier requires two target gain functions in terms of T-N, to be used in two sequential non-linear optimization procedures, respectively. An amplifier with a flat gain of similar to 10 dB operating in 0.8-2.35 GHz is designed using a small-signal model of an experimental GaN-HEMT. Theoretical amplifier performance obtained in Matlab is shown to be in excellent agreement with the simulated performance in MWO (Microwave Office, AWR Inc.). A prototype low-power amplifier having a similar to 10 to 12 dB gain, operating in (0.9-1.5 GHz) is also produced and measured which yielded good performance results.Yayın A design technique of 50 Ω terminated bandpass matching network and its implementation to a Y-shaped monopole antenna matching(Springer, 2016-12) Aydın, Çağatay; Atilla, Doğu Çağdaş; Köprü, Ramazan; Kılınç, Sedat; Karakuş, Cahit; Yarman, Bekir Sıddık BinboğaIn this paper, a 50 Ω terminated or in other words transformerless bandpass matching network design methodology and an implementation example are presented. The real frequency techniques are powerful numerical methods to design wideband lossless two-port networks such as filters, matching networks and amplifiers. In these techniques, the value of the termination resistance of the designed network could not be yielded as 50 Ω by numerical package. Hence, a transformer is also required for 50 Ω termination which is not practical for high frequency applications. By employing the proposed procedure, it is guaranteed to obtain transformerless bandpass matching network. Also in this study a wideband suspended monopole antenna is examined. The proposed antenna consists of two major elements; Y-shaped impedance matching plate and hemi-circular radiator. Moreover Y-shaped impedance matching plate connected to a feeding probe excites the suspended hemi-circular radiator via air gap. Consequently, a transformerless bandpass matching network is designed to filter and expand the operational frequency bandwidth of the proposed antenna. It has been observed that ideal circuit and the layout of the matching network simulation have good agreement.Yayın Ultra wideband matching network design for a V-shaped square planar monopole antenna(Cambridge University Press, 2014-12) Köprü, Ramazan; Kılınç, Sedat; Aydın, Çağatay; Atilla, Doğu Çağdaş; Karakuş, Cahit; Yarman, Bekir Sıddık BinboğaIn this paper, design, manufacture, and measurement of a wideband matching network for a broadband V-shaped square planar monopole antenna (V-SPMA) is presented. Matching network design is unavoidable in most cases even vital to facilitate a maximally flat power transfer gain for an antenna. In the work, a bandpass matching network (BPMN) design is done for a particular square monopole antenna with V-shaped coupling element that has essentially bandwidth increasing effect. Designed BPMN and the antenna forms a VSPMA-BPMN matched antenna structure. "real frequency technique" is employed in the BPMN design. BPMN prototype circuit has been constructed on an FR4 laminate with commercial microwave chip inductors and capacitors. Vector network analyzer gain and reflectance measurements of the matched antenna structure have shown highly compatible results to those of the theoretical design simulations along the passband (similar to 0.8-4.7 GHz). Furthermore, newly proposed distributed capacitor-resistor lossy model for microstrip lines used in the BPMN circuit have exhibited that it can successfully mimic the measured gain and reflectance performance of the matched structure in passband and even in stopband upto 8 GHz. Designed structure can be utilized as a one single wideband broadcasting medium suitable for many communication standards such as GSM, 3G, and Wi-Fi.Yayın Multiband filter design using generalized mapping functions and synthesis with lumped resonators(Czech Technical University, 2020-06-01) Yıldız, Serkan; Aksen, Ahmet; Kılınç, Sedat; Yarman, Bekir Sıddık BinboğaIn this paper, a new multiband frequency mapping function is proposed to design multiband filter. The presented mapping function is a generalized form of the sequential low pass to band pass (LPtoBP) transformation. The multiband filter design is based on the application of the frequency mapping function on a LP prototype. The synthesis of the resulting multiband filter is obtained by lumped element resonators. Several examples are presented to validate the proposed design approach. A triple band filter implementation and measurement results are presented.Yayın Low pass filter design with improved stop-band suppression and synthesis with transformer-free ladders(John Wiley and Sons Inc, 2021-09) Yıldız, Serkan; Aksen, Ahmet; Kılınç, Sedat; Yarman, Bekir Sıddık BinboğaA new method to design transformer-free low pass (LP) ladder network with improved stop-band suppression performance is introduced. The parametric representation of back-end impedance of LP filter network is established with minimum impedance part and a Foster reactance part. The constructed impedance function is optimized by using real frequency technique. It has been shown that the proposed method provides LP filters which have superior stop-band suppression in comparison with classical transfer function-based filters with same complexity. The synthesis of the LP filter is obtained with the proposed element extraction procedure and resulted with fully realizable network elements in ladder form. An LP filter design and application by employing the proposed technique is provided. The measurement results of the prototyped filter are presented.Yayın Novel approach to design ultra wideband microwave amplifiers: Normalized gain function method(Spolecnost Pro Radioelektronicke Inzenyrstvi, 2013-09) Köprü, Ramazan; Kuntman, Hulusi Hakan; Yarman, Bekir Sıddık BinboğaIn this work, we propose a novel approach called "Normalized Gain Function (NGF) method" to design low/medium power single stage ultra wide band microwave amplifiers based on linear S parameters of the active device. Normalized Gain Function T-NGF is defined as the ratio of T and vertical bar S-21 vertical bar(2), desired shape or frequency response of the gain function of the-amplifier to be designed and the shape of the transistor forward gain function, respectively. Synthesis of input/output matching networks (IMN/OMN) of the amplifier requires mathematically generated target gain functions to be tracked in two different nonlinear optimization processes. In this manner, NGF not only facilitates a mathematical base to share the amplifier gain function into such two distinct target gain functions, but also allows their precise computation in terms of T-NGF=T/vertical bar S-21 vertical bar(2) at the very beginning of the design. The particular ainplifier presented as the design example operates over 800-5200 MHz to target GSM, UNITS,. Wi-Fi and WiMAX applications. An SRFT (Simplified Real Frequency Technique) based design example supported by simulations in MWO (Micro Wave Office from AWR Corporation) is given using a 1400 mW pHEMT transistor, TGF2021-01 from TriQuint Semiconductor.Yayın Dual band stop filter design via frequency transformation and synthesis with lumped resonators(Institution of Engineering and Technology, 2020-05-01) Yıldız, Serkan; Aksen, Ahmet; Kılınç, Sedat; Yarman, Bekir Sıddık BinboğaThis study presents a new compact design technique for dual band stop (DBS) filter. Analytical formulation of DBS frequency transformation/mapping is derived in terms of parametric representation of band characteristic of DBS filter. The analytical derivation of the transformation function is based on sequential application of classical low pass to band stop (LP to BS) and low pass to band pass (LP to BP) transformations. Assigned band characteristic of DBS filter can be achieved by applying the proposed transformation function on an LP prototype network. The explicit network topologies for DBS reactance mapping are presented. Several numerical examples are provided to validate the proposed mapping function. An implantation example of DBS filter for GSM900 and GSM1800/UMTS bands is given. Mixed element realisation of the designed filter and measurement results of the design are presented.
