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Öğe 3D printed stacked antenna for WLAN drone communication(Yildiz Technical University, 2023) Belen, Aysu; Tetık, Evrim; Başak, HasanUnmanned Aerial Vehicle or drone technologies have spread rapidly into areas such as search and rescue, monitoring, surveillance, emergency assistance, delivery of goods, and aerial photography and video. The design of compact, low cost, and multi resonant frequency antenna models has become a critical research study for these applications. Although one of the most popular antenna designs that have such specifications are Microstrip Patch Antennas (MPA), they have the handicap of narrow operation band. Stacking is one of the techniques that not only improve the bandwidth of the antenna but also makes it possible to increase its gain and expand its operation band. Herein, design of a low cost low weight wideband Stacked (MPA) design suitable for WLAN drone communication applications is studied. By using unique features of 3D printing technology the proposed design will be prototyped for satisfying the aimed design goals. For this purpose, the antenna is simulated in CST Microwave Studio by a 3D electromagnetic based model, and maximum gain level that is approaching 9.3 dBi at 5.8 GHz frequency has been achieved. Next, the antenna design is prototyped using 3D printing technology, and a gain level of 7.5, 8.3 dBi are measured at the operating frequencies 5.2 GHz and 5.8 GHz WLAN applications. The results show that the proposed antenna achieves higher performance than its counterparts in literature based on measures such as operation bandwidth, gain, size and manufacturing costs.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 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 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 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 systems
