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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 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 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 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 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 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 A novel design of non-uniform reflectarrays with symbolic regression and its realization using 3-D printer(Applied Computational Electromagnetics Society, 2019) Mahouti, Peyman; Güneş, Filiz; Belen, Mehmet Ali; Çalışkan, AlperHerein, a novel design of an X-band Non-Uniform Reflectarray Antenna (NURA) with Symbolic Regression SR and its fabrication using 3D Printer technology are presented. A NURA is consist of simply a grounded dielectric layer with the variable thickness. Firstly, SR is employed to obtain with a great accuracy for the reflection phase characteristics of a grounded dielectric layer in the analytical form within the continuous domain of 1 <=epsilon(r)<= 6 and thickness 0.1 <= h <= 3 mm for the X-band. For this purpose, SR is trained and validated by the 3D CST Microwave Studio data. Then, for the design purpose of NURA, a special fine reflection calibration characteristic is built up again by SR with the sufficient reflection phase range of the 3D Printer's material at the operation frequency 10 GHz. In the third step, the designed NURA is then prototyped by using 3D printer technology where the material can be easily shaped and create unit cell at printing accuracy of 0.1 mm per layer. Thus, by this mean the prototyping cost of non-uniform Reflectarray design can be reduced drastically both in means of time and ease of manufacturing. In the final step, mismatching and radiation properties of the prototyped NURA are measured.Öğe Performance enhancement of a microstrip patch antenna using substrate integrated waveguide frequency selective surface for ISM band applications(Wiley, 2018) Güneş, Filiz; Belen, Mehmet Ali; Mahouti, PeymanIn this work, performance enhancement of a microstrip patch antenna working at ISM band (2.4 GHz) is presented using modified cross shaped Frequency Selective Surface (FSS) constructed on Substrate Integrated Waveguide (SIW). Design optimizations and simulations of both the antennas and FSS are carried out on low-cost FR4 substrate (with (r)=4.4, h=1.58 mm, and tan =0.0035) in the 3D CST MSW environment. In addition, to exhibit merit of using SIW structure, the traditional FSS in the same configuration is also applied and performances of the antennas used FSSs with and without SIW are also simulated and compared in the 3D CST MSW environment. Finally, the proposed model is confirmed by measurements agreed with the theoretical results to have enhanced gain and beam width at the 2.4 GHz bandwidth alongside improvement in the return loss.Öğe Realization of dielectric sheets for gain ımprovement of ultra-wideband horn antennas using 3d printer technology(Applied Computational Electromagnetics Society, 2019) Belen, Mehmet Ali; Mahouti, PeymanIn this work, 3D printing technology had been used to prototyped 10 dielectric sheets with relative dielectric constant of 2.5 for gain improvement of a TEM horn antenna. By loading the 3D printed dielectric sheets to the aperture of the horn antenna it is achieved to improve the radiation performance of the antenna over an ultra-wide operation band of 2-13 GHz. Here the Periodic dielectric sheets are designed to function similarly to a dielectric lens for focusing the incoming electromagnetic waves to increase directivity properties, while keeping their mismatching characteristics with less size and low manufacturing cost compared to its counterpart lens designs. The dielectric sheets had been prototyped via the use of 3D printing technology for experimental measurements. The measured performance of the proposed 3D printed dielectric loaded TEM horn antenna is compared with its counterpart ultra-wide band gain improvement methods for horn antennas in literature. From the measured results of the prototyped module, not only the proposed 3D printed dielectric sheets are smaller and have lower cost compared to their counterpart designs but also achieves to improve the gain characteristics of the antenna design over an ultra-wide band operation band without a distortion on antenna's S-11 characteristics.Öğe Symbolic regression for derivation of an accurate analytical formulation using "Big Data": An application example(Applied Computational Electromagnetics Society, 2017) Mahouti, Peyman; Güneş, Filiz; Belen, Mehmet Ali; Demirel, SalihWith emerging of the Big Data era, sample datasets are becoming increasingly large. One of the recently proposed algorithms for Big Data applications is Symbolic Regression (SR). SR is a type of regression analysis that performs a search within mathematical expression domain to generate an analytical expression that fits large size dataset. SR is capable of finding intrinsic relationships within the dataset to obtain an accurate model. Herein, for the first time in literature, SR is applied to derivate a full-wave simulation based analytical expression for the characteristic impedance Z(0) of microstrip lines using Big Data obtained from an 3D-EM simulator, in terms of only its real parameters which are substrate dielectric constant a, height h and strip width w within 1-10 GHz band. The obtained expression is compared with the targeted simulation data together with the other analytical counterpart expressions of Z(0) for different types of error function. It can be concluded that SR is a suitable algorithm for obtaining accurate analytical expressions where the size of the available data is large and the interrelations within the data are highly complex, to be used in Electromagnetic analysis and designs.Öğe UWB gain enhancement of horn antennas using miniaturized frequency selective surface(Applied Computational Electromagnetics Society, 2018) Belen, Mehmet Ali; Güneş, Filiz; Mahouti, Peyman; Belen, AysuIn this work, enhancement of the radiation performances of horn antennas are worked out within their operation bandwidth by placing the miniaturized Frequency Selective Surface (FSS)s perpendicularly into the inner part of their flares. Here each FSS consists of only a single miniaturized double-sided inverted Tshaped square unit cell designed on the low-cost FR4 with relative permittivity 4.4, loss tangent 0.0035 and thickness 1.58 mm in 3D CST environment so that it is able to focus the propagating electromagnetic waves to increase the directivity properties like a dielectric lens, while keeping the mismatching characteristics with less size and low manufacturing cost compared to its counter parts. Herein an exponentially tapered TEM horn with the operation bandwidth of 5-13 GHz is taken as an example horn antenna for measurements. From the measured results of the prototyped module, it can be observed that the proposed module keep mismatching characteristics of the horn antenna, meanwhile the gain and beam widths are enhanced to amplify the signal in the operation band without any increase in the total volume of the module or making the design bulky. Thus, it is expected that this methodology can be implemented to horn antennas effectively reducing volume and cost of communication systemsÖğe An UWB vivaldi antenna with the enhanced functionalities through the use of DGS and dielectric lens(IEEE, 2017) Belen, Mehmet Ali; Evranos, İlhan Ömer; Güneş, Filiz; Mahouti, PeymanNowadays UWB antennae have become popular due to the growing need for both the UWB ground and space communication. In this work, an UWB Vivaldi antenna is proposed with the enhanced functionalities through the use of DGS and dielectric lens for to be used for both ground and space communications. Performance enhancement of an UWB Vivaldi antenna is worked out on Roger 4350B substrate (epsilon(r)=3.66, ran delta=1.58mm) within the bandwidth of 1-14 GHz using the CST Microwave Studio environment. For the purpose, Defected Ground Structure (DGS) and dielectric lens are used in the low and high frequency regions, respectively. In this work, Vivaldi antenna structure is particularly preferred due to its cost-effective and simple manufacturing over 1 GHz. Furthermore, performance enhancement of the antenna also verified experimentally as compared with the simulated return loss and radiation gain characteristics within the 1-14 GHz bandwidth.
