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Öğe 3D printed wideband flat gain multilayer nonuniform reflectarray antenna for X-band applications(Wiley, 2020) Belen, Aysu; Güneş, Filiz; Belen, Mehmet Ali; Mahouti, PeymanReflectarray antenna designs have become an efficient solution alternative totheir counterpart designs due to their beam scanning capability, low profile, highgain, and mounting flexibility. Herein, design and realization of a wideband, flatgain multi-layer nonuniform reflectarray (MNURA) using 3D printing technologyis presented. Design optimization of the proposed MNURA has been achieved inthe two stages: First, a 3D CST Microwave Studio based Multilayer PerceptronNeural Network (MLP NN) model establishes the reflection phase characteristicof the MNURA unit element as an accurate continuous function of the geometri-cal design parameters and dielectric constant. Then Differential EvolutionaryAlgorithm DEA is selected as a powerful optimization algorithm for determiningthe optimum geometrical design parameters and dielectric constant of MNURAthroughout the X-band to have a large range, wideband, and flat gain RA design.3D printing technology has been used for prototyping of the proposed MNURAdesign. Here, the resulted optimum dielectric constant value of 2.2 is realized by56% infill rate of“Polar White”PLA using the relation between the infill rate anddielectric constant. The prototyped antenna has a total size of 300×300 (mm),and its measured performance characteristics achieve a wideband flat gain of23.2 dBi with a ripple level of almost 1.5 dBi and return loss characteristic of lessthan?10 dB over the operation band of 8 to 12 GHz.Öğe Active inductor design for reconfigurable bandpass microstrip filter applications(Applied Computational Electromagnetics Society, 2019) Belen, Mehmet Ali; Mahouti, PeymanHerein, the design of an active inductor and its typical application for a reconfigurable band-pass filter circuit are presented. The Active Inductor design consists of a passive variable phase and amplitude compensating network and a highly linear inverting amplifier in order to form a gyrator-C design. The design allows a wide frequency range for tuning the equivalent inductance and resistance values that enable it to be used as a filter design where the inductor equivalent resistance increases and improves signal rejection for band-pass filter applications. As a typical application, first-order active band-pass filter had been designed and prototyped. The simulation and measurement results of the design are compared with the performance results of counterpart designs in literature. From the experimental results, it can be concluded that the proposed design is a suitable model for design of tunable band pass filter circuits. The design has an operation band of 0.7-2.1GHz with the equivalent inductance value of 2.6nH.Öğe Artificial neural network application for novel 3D printed nonuniform ceramic reflectarray antenna(Wiley, 2020) Mahouti, Mehran; Kuşkonmaz, Nilgün; Mahouti, Peyman; Belen, Mehmet Ali; Palandöken, MerihThe main inconvenience in design process of modern high performance reflec-tarray antennas is that these designs are heavily depended on full-wave electro-magnetic simulation tools, where in most of the cases the design optimizationprocess would be an inefficient or impractical. However, thanks to the recentadvances in computer-aided design and advanced hardware systems, artificialneural networks based modeling of microwave systems has become a popularresearch topic. Herein, design optimization of an alumina-based ceramic sub-strate reflectarray antenna by using multilayer perceptron (MLP) and 3D printingtechnology had been presented. MLP-based model of ceramic reflectarray (CRA)unit element is used as a fast, accurate, and reliable surrogated model for the pre-diction of reflection phase of the incoming EM wave on the CRA unit cell withrespect to the variation of unit elements design parameters, operation frequency,and substrate thickness. The structural design of a reflectarray antenna with non-uniform reflector height operating in Xband has been fabricated for the experi-mental measurement of reflectarray performance using 3D printer technology.The horn feeding based CRA antenna has a measured gain characteristic of22 dBi. The performance of the prototyped CRA antenna is compared with thecounterpart reflectarray antenna designs in the literature.Öğe Blade antenna design for UHF applications(IEEE, 2018) Belen, Aysu; Partal, Hakan Pasa; Ördek, Sezgin; Belen, Mehmet AliThe importance of today's wireless communication systems are ever increasing due to the high demand. With the development and common usage of the next generation wireless communication devices the need of high rate data transfer is increased. Herein design and measurement of a low cost high gain blade antenna for 600-3000 MHz UHF band is studied. In order to achieve a wide band high gain radiation characteristic a wide band range impedance matching over the operation band is done. The proposed design allows usage of a single antenna model over the wide operation frequency band instead of multi antenna models. Thus, with this model it is possible to reduce both the size of communication system and its cost. In this proposed blade antenna design, by creating gaps on the antennas surface a wide range impedance matching is achieved due to the change of surface current distribution. As it can be observed from the measurement results the proposed antenna's return loss characteristic is less than -6db, and has a gain characteristic of 4.5-6.2 dB over the operation band.Öğe Competitive evolutionary algorithms for building performance database of a microwave transistor(Wiley, 2018) Güneş, Filiz; Belen, Mehmet Ali; Mahouti, PeymanIn this work, the simultaneous trade-off relations among the noise figure F, gain G(T), input V-in, and output V-out VSWRs of a microwave transistor operated at a certain (V-DS, I-DS, f) condition are obtained fast and as accurate as the corresponding analytical results using multiobjective optimization process without any need for expertise on the microwave device, circuit, and noise. Three powerful evolutionary algorithms, cuckoo search, firefly, and differential evolution, are implemented comparatively as a study case to obtain the trade-off relations of a typical low-noise amplifier transistor NE3511S02 for its operation between 9 and 17GHz at V-DS=2V and I-DS=10mA. Finally, differential evolution is found as the most successful algorithm to demonstrate the typical trade-off relations of NE3511S02. It can be concluded that these trade-off relations being obtained by using a signal and noise model of the transistor enable performance database covering all the (FFmin, G(T), V(in)1, V(out)1) quadruples with their (Z(S), Z(L)) termination pairs using solely an evolutionary optimization process. Thus, a small signal transistor can be identified by its performance database to be used in the design optimization of high-performance low-noise amplifiers with the full device capacity.Öğe Deep learning base modified MLP model for precise scattering parameter prediction of capacitive feed antenna(Wiley, 2020) Çalık, Nurullah; Belen, Mehmet Ali; Mahouti, PeymanThe relations between the antennas' geometrical parameters and design specifi-cations usually consist of linear and nonlinear components. Especially with theincrease of the requested performance measures, the design procedure becomesmuch more complex due to the conflicting performance criteria or designlimitations. To achieve a design with high performance with feasible designparameters, a fast, accurate, and reliable design optimization process is required.Herein, to have a fast, accurate, and high-performance capacitive-feed antennamodel to be used in design optimization problems, a modified multi-layerperceptron (M2LP) model has been proposed. The M2LP is an equivalent con-volutional neural network (CNN) model of a standard multilayer perceptron(MLP), where instead of traditional training parameters of MLP, more advancedtraining parameters of CNN models such as batch-norm layer, leaky-rectifiedlinear unit (ReLU) layer, and Adam training algorithm had been used. Further-more, the M2LP model had been used in a design optimization process and theobtained optimal antenna had been prototyped using 3D printing technology forjustification of the proposed M2LP model with experimental results. As can beseen from the results, the proposed M2LP model is a fast, accurate, and reliableregression model for design optimization of microwave antennas.Öğe Design and implementation of a RF energy harvesting module with DC power control(Institute of Electrical and Electronics Engineers Inc., 2018) Partal, Hakan P.; Partal, Sibel Zorlu; Belen, Mehmet AliIn this experimental research paper, a zero-bias RF energy rectifying antenna (rectenna) is designed at an ISM band, DC output is amplified by employing DC boost converters, and DC energy is stored on super-capacitors. The rectenna is analyzed for low power detection and rectification efficiencies, impedance matching network is implemented to reduce the reflected RF power at the rectifiers' input, DC to DC converters are evaluated for their compatibility to the rectifiers, and super-capacitor behaviors are investigated for their charging time and adaptability as wirelessly chargeable batteries. Many practical concerns and experiences are discussed for the RF energy harvesting systems' potential implementations on low power sensors and wireless communications network.Öğe Design and implementation of doppler microwave motion sensor for indoor application(Yıldız Teknik Üniversitesi, 2018) Belen, Mehmet Ali; Mahouti, Peyman; Güneş, Filiz; Partal, Hakan PasaThis paper presents a systematic integration and circuits design scheme of ISM-band Doppler radar for shortrange applications. The authors designed a complete CW Doppler radar transceiver and made a test for verification. Firstly, we establish a system model by conventional radar equation. Secondly, design the schematics of main modules including an oscillator, a mixer, and antennas. Finally, perform system integration using the designed circuits diagrams and parameters. The performance is found fairly satisfactory by test verificationÖğe Design and manufactering of an X-band horn antenna using 3-D printing technology(IEEE, 2017) Toy, Yunus Can; Mahouti, Peyman; Güneş, Filiz; Belen, Mehmet AliHerein, design and manufacturing of an X-band pyramid horn antenna using 3-D printer is studied with its experimental results. X-band is used for the military purposes with the marine and satellite technology based on the geographic discovery. Horn antennas are especially very preferable in these applications since they can be built easily at the different types depending on their utilizations and provide low voltage standing wave ratios. This work is focused on a pyramid horn antenna design and its manufacturing method with 3-D printer technology. The measurement results of the 3-D printed antenna are also compared with the simulation results.Öğe Design and realization of an ultra-low power sensing RF energy harvesting module with its RF and DC sub-components(Wiley, 2019) Partal, Hakan Pasa; Belen, Mehmet Ali; Partal, Sibel ZorluHerein, design, development, and analysis of ultra-low power sensing energy harvesting modules and their subcomponents for ISM band applications have been studied with a holistic approach in an effort to achieve a feasible and high efficient RF energy harvesting performance. The complete harvester system designed and developed here consists of a zero-bias RF energy rectifying antenna (rectenna), DC boost converters and energy storage super-capacitors. Compared with the counterpart energy sources, the surrounding or transmitted wireless energy has low intensity which requires designs with high efficiency. To achieve a successful harvester performance, rectifier circuits with high sensitivity Schottky diodes and proper impedance matching circuits are designed. Dedicated RF signals at various levels from nanowatts to miliwatts are applied at the input of the rectenna and the measured input power versus the scavenged DC output voltage are tabulated. Furthermore, by connecting the rectifier to a high gain antenna and using a RF signal transmitter, the wireless RF power harvesting performance at 2.4 GHz was tested up to 5 m. The performance of the rectenna is analyzed for both low-power detection and efficiencies. Impedance matching network is implemented to reduce the reflected input RF power, DC to DC converters are evaluated for their compatibility to the rectifiers, and super-capacitor behaviors are investigated for their charging and storage capabilities. The measured results indicate that a wide operating power range with an ultra-low power sensing and conversion performance have been achieved by optimizing the efficiency of the Schottky rectifier as low as -50dBm. The system can be used for battery free applications or expanding battery life for ultra-low power electronics, such as; RFID, LoRa, Bluetooth, ZigBee, and low power remote sensor systems.Öğe Design and realization of dual band stacked antenna via three-dimensional printing technology(Wiley, 2020) Belen, Mehmet AliWith the ever-increasing demands for high-performancewireless communication systems, the need of fast andlow-cost realization of antenna stages had also becomemore crucial for wireless communication industry.Herein, design and low-cost realization of a three-dimensional (3D) printed dual band Stacked Micro-strip Patch Array (SMPA) antenna has been studied. A3D electromagnetic-based simulation model of the pro-posed SMPA antenna has been created in CST Micro-wave Studio. The antenna achieves a simulated gainlevel of almost 8.3 dBi at 5.2 and 10.4 GHz frequen-cies. Then, the antenna design with optimally selectedparameters has been prototyped via the use of 3Dprinting technology. The prototyped antenna has ameasured gain level of 7.2 dBi at the operation fre-quencies. Furthermore, the experimental results of theprototyped antenna have been compared with the sim-ulated results. From the compared results, it can beconcluded that not only the proposed antenna designhas achieved high-performance measures comparedwith counterpart designs in the literature but also it ispossible to achieve an accurate, fast, and low-cost real-ization via the use of 3D printing technologyÖğe Design and realization of multilayered cylindrical dielectric lens antenna using 3D printing technology(Wiley, 2019) Mahouti, Peyman; Belen, Mehmet Ali; Güneş, Filiz; Yurt, ReyhanHerein, design and realization of a novel, low cost, small size, high gain, 3D printed multilayered cylindrical dielectric lens antenna (MLCDLA) is presented at 10 GHz. In the first stage, MLCDLA is designed suitable the 3D printed technology in CST 3D EM simulation environment. Then gain, return loss, and radiation pattern of the design are investigated in the X-band frequencies in the same 3D simulated environment. In the second stage, the designed lens is fabricated by the 3D printed technology in dimensions of 30 x 30 x 52.5 mm(3) using acrylonitrile butadiene styrene, with epsilon(r)=2.5. In the final stage, performance characteristics of the proposed LCDLA are measured using 10 GHz rectangular waveguide as feeding unit and are compared with the simulated results and counterpart designs in literature. The prototyped MLCDLA is achieved 14 dBi measured gain at 10 GHz. It can be concluded that the proposed 3D printing method not only enables a high performance MLCDLA design but also provides its fast, low cost, and effective prototyping process which can be used for other microwave devices.Öğe Design and realization of novel frequency selective surface loaded dielectric resonator antenna via 3D printing technology(JOHN WILEY & SONS LTD, 2020) Belen, Mehmet Ali; Mahouti, Peyman; Palandöken, MerihOne frequently addressed technique for the performance enhancement of radiating elements in the form of microstrip antennas is the utilization of dielectric resonators. A dielectric resonator antenna (DRA) has a conventional structural formation similar to any microstrip patch antenna where, at least, one additional dielectric layer has been placed over the radiating element. In this paper, it is aimed to propose a high performance, easy to prototype, light weight, and low cost DRA in combination with frequency selective surfaces (FSS) for ISM band applications using 3D printing technology. The proposed 3D printed FSS loaded DRA has a measured gain of 5.6 dBi with S11 level less than ?10 dB in the operation band between 1.98 and 2.68 GHz. Furthermore, the measured performance of 3D printed antenna is compared with the counterpart alternative antenna designs in the literature for the similar application fields. The novel FSS loaded DRA is not only much smaller than the counterpart antenna designs but also has a moderate gain characteristics which makes the proposed antenna design an optimal RF solution for ISM band wireless communication applications.Öğe Design and realization of quasi Yagi antenna for indoor application with 3D printing technology(Wiley, 2018) Belen, Mehmet Ali; Mahouti, PeymanWith the advances in the extrusion depositing base three-dimensional (3D) printing technology and decreases intheir costs, these technologies are being used in manyfields for fast and low cost prototyping means. One ofthese applications is manufacturing of microwave circuits.Herein, design and realization of quasi Yagi antenna forindoor application with 3D printing technology is pre-sented. First, design of a wide band microstrip quasi Yagiantenna consists of a dipole fed by a coplanar strip line, arectangular patch, and a ground reflector is studied. Thesize of the antenna is reduced by using a half bowtieshaped dipole and reflector. The studied microstrip quasiYagi antenna is aimed to operate within the operation fre-quency range of 670–3000 MHz. Then for experimentalresults, the designed antenna is fabricated by using a 3Dprinter with poly(lactide acid) material. From observingthe experiment results it can be concluded that 3D printedantenna has good performance, within the operation bandwith a good return loss characteristic performance of lessthan210 dB and a moderate gain of 3.5–4.6 dBi. As itcan be seen, the 3D printer technology is an efficientmethod for fast and accurate prototyping of antennadesignÖğe Design of nonuniform substrate dielectric lens antennas using 3D printing technology(Wiley, 2019) Belen, Mehmet Ali; Mahouti, PeymanWith the latest developments in 3D printing technologies and decreases in their costs, these prototyping methods are now being used extensively in many applications for fast, low-cost, and precise prototyping. In this work, 3D printing technology had been used for prototyping of nonuniform substrate dielectric lens antennas. For this, two study cases had been taken into consideration: (a) design of a dielectric lens antenna with 25 nonuniform height dielectric pillars with constant dielectric value, and (b) design of a dielectric lens antenna with 25 pillars of nonuniform dielectric constant value but equal height. Both of the designs, first, were modeled in 3D EM simulation environments and then were prototyped via 3D printing technology. Both the simulations and measured results of the prototyped antennas were compared and found that they were agreeable. Both of the antenna designs achieved a measured gain level of almost 17.4 dBi at 10 GHz, with a return loss of less than -10 dB. Thus, as it can be observed from the experimental results, the proposed 3D printing-based manufacturing process is an efficient solution for the realization of high-performance nonuniform substrate dielectric lens antennas that are either difficult or impractical with conventional prototyping methods.Öğe Gain enhancement of antipodal vivaldi antenna(IEEE, 2018) Belen, Mehmet Ali; Evranos, İlhan Ömer; Güneş, FilizDue to the broadband requirements in the field of communication, Ultra-Wide Band antennas have become popular nowadays. In this study, an antipodal Vivaldi antenna with UWB and compact design was investigated for X band applications. The antenna features have been developed using Defective Ground Surfaces (DGS) and dielectric lenses. The Vivaldi antenna was designed in the CST Microwave Studio Environment to work with RTDroid5880 material (dielectric constant=4.88, height= 0.76mm) in the 8-12 GHz band range. In this study, the Vivaldi antenna structure was chosen; because it is cost-effective and easily producible in production over 1 GHz. In addition, the performance enhancement of the antenna in the study is given in the bandwidth of 8-12 GHz in terms of simulated return loss and propagation gain characteristics.Öğe GSM filtering of horn antennas using modified double square frequency selective surface(Wiley, 2017) Güneş, Filiz; Sharipov, Zafar; Belen, Mehmet Ali; Mahouti, PeymanIn this work, a dual-band frequency selective surface (FSS) is proposed to be placed perpendicularly into the apertures of horn antennas for prefiltering 900 and 1800 MHz GSM signals interfering during the signal reception, with the enhanced return loss, gain, and directivity at the desired frequencies. For this purpose, the microstrip double square loop MDSL is modified in the first stage. As for the second stage, an FSS array (2x2) is built up arranging the unit MDSLs in a periodic structure and finally these FSS unit arrays are fixed perpendicularly covering the aperture of a ridged horn antenna which is a part of the available radar system operating between 0.5 and 3 GHz in our laboratory, to construct an integrated module having both bandstop prefilter and horn antenna called filtenna. The simulated and experimental results are agreed that the proposed FSS structure attenuates GSM signals at the 900 and 1800 MHz through the high reflection and very poor transmission mechanisms meanwhile enhances return loss characteristics, radiation pattern, and gain of the horn antenna in the desired band. Thus, it can be concluded that these simple microstrip FSS structure can be effectively adapted to the horn antennas which need the GSM prefiltering.Öğe Microstrip tapered traveling wave antenna for wide range of beam scanning in X- and Ku-bands(Wiley, 2019) Güneş, Filiz; Belen, Aysu; Belen, Mehmet AliIn this work, a broadband traveling wave antenna (TWA) is presented as a microstrip design that is capable of a wide range of beam scanning by changing the operation frequency within 8 to 14 GHz. For this purpose, a rhombus shaped microstrip patch is used as a unit element and TWA is built as a tapered microstrip line consisting of the cascaded rhombus shaped unit elements and terminated by a rectangular antenna instead of traditional resistive termination which can be called patch loaded traveling wave antenna (PLTWA). Optimization and simulation of the PLTWA is carried out using 3-D Microwave simulation software CST and its dimensions are resulted as 130 x 30 mm. From the simulations, it should be noted that the patch termination increases the maximum gain almost 3 dB and the total efficiency up to 90% compared to the traditional resistive load over the operation band at the expanse of a small distortion on S-11 characteristics. Then the PLTWA is fabricated and measured along its operation band 8 to 14 GHz and it exhibits a peak gain of 9.5 dBi at 11 GHz. The measured gain of the proposed antenna is found between 9 dB and 12 dB and its beam direction is steerable with the range of 80 degrees (-65 degrees-15 degrees) over the operation band 8 to 14 degrees GHz.Öğe Modeling and realization of cavity-backed dual band SIW antenna(Applied Computational Electromagnetics Society, 2017) Belen, Mehmet Ali; Mahouti, Peyman; Çalışkan, Alper; Belen, AysuHerein, substrate integrated waveguide technology is applied in order to design high performance dual-band microstrip patch antennas. Two microstrip patch antenna designs were studied and modeled in 3D electromagnetic simulators. The obtained optimal models were then realized and measured. The measurement performance of the proposed antenna designs were then measured for 2.4 and 5.6 GHz. The results suggest that the proposed model consisting of a modified microstrip cavity-backed antenna and a defected ground structure is a high performance and low cost solution for 2.4 and 5.6 GHz applications.Öğe Narrow dual band frequency selective surface design for X-band application(IEEE, 2018) Belen, Mehmet Ali; Gülseren, Ahmet H.; Güneş, FilizIn today's world where communication is very important, studies on communication systems are continuing rapidly to increase the quality of communication. For this reason, in order to be able to develop in important areas such as communication and radar systems, antenna design studies with different characteristics are gaining importance. Especially in the field of microwave several application have been done by using metamarials. In this study, a band stop dual-band frequency selective surface is proposed in the X band frequencies using a single layer interdigital capacitor structure. When the line widths and gaps on the interdigital capacitor structure are changed, a tunable FSS with dual band resonance frequencies at frequencies of 8-10 GHz is proposed. FR4(eps 4.6, h:1.58mm) is used in FSS design. The unit cell size is 22.2 x 16.6 mm.
