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Öğe Antipodal Vivaldi Antenna for Passive Imaging Technology in Ka Frequency Band(2018) Duman, Mehmet; Salman, Alp OralAntenna is one of the most important part in Passive Millimeterwave Imaging (PMI) Technology which isused to view scene in foggy air conditions or to see concealed weapon under clothes that cannot be seenother technology because of the materials of weapon. There are some frequency windows to work withPMI Technology as 35, 96 and 220 GHz and it is near 35 GHz frequency window for this work. AntipodalVivaldi Antenna has 50.07 ohm input impedance, Z, for matching, and -39.23 dB input reflectioncoefficient, S11, and 6.82 dB gain, G, is designed for 35.18 GHz center frequency in Computer SimulationTechnology (CST) Program. The antenna has 110 MHz bandwidth and it can work between 35.23 GHz and35.12 GHz frequencies. After the antenna is connected to the amplifier or detector circuits, the createdsystem will be integrated into a scanner which is capable of scanning azimuth and elevation axes. As aresult, PMI System will be formed and ready to view the scene or the hidden things in haze air conditions.Öğe Attenuation of EM Waves Emitted from Inset Feed Type Microstrip Rectangular Patch Antenna by Wet Snow(Gazi Univ, 2022) Özkan, Rabia; Mert, Oğuzhan; Yılmaz, Yusuf; Ramazan, Feyza; Duman, MehmetMicrostrip patch antennas stand out because of their low cost, smaller size and easy fabrication. The study presents the design of a microstrip rectangular patch antenna operating at 2.6 GHz frequency and the effect of different weather conditions on the antenna. During the antenna design on CST program and manufacturing in the laboratory, it is aimed to perform the measurement at the desired frequency and decibel level. The study includes experiments and results made on different types of snow, apart from the normal measurement with the VNA. A good S11 scattering value was obtained at the desired frequency in the designed microstrip patch antenna as-18.48 dB. This value decreased to around-5 dB when there was wet snow on the antenna due to attenuation and thermal effects. If the snow was removed from the antenna, the old S11 value could not be returned because of the wetness left by the snow, and it remained at approximately-14 dB. Consequently, the attenuation of the electromagnetic waves have been confirmed by the literature under different conditions as wet snow with nano VNA for the first time. Attenuation by wet snow and water is greater than dry snow with voids.Öğe Butterworth BPF design and analysis with using lumped elements, transmission lines and combined factors for C band(Pamukkale Univ, 2024) Duman, MehmetIn the field of electronics, technological advancements bring about alterations in electronic devices. With the fast -paced advancements in the era of communication, the frequency bands are becoming congested. One of the frequencies utilized by Wi-Fi-6, 6 GHz, has garnered its share of attention in these changes. This study proposes the design of a Butterworth Bandpass Filter that can be utilized in the IEEE C Band, employing both lumped elements and microstrip transmission lines. The methodology for determining the length and width of the transmission lines, as well as the considerations taken into account during their modification, is provided. A composite filter comprising of both elements and lines is also presented. The combined filter design is aimed at resolving issues arising from the increasing frequency. During the design process, an 8th -order lowpass filter is generated using the Butterworth normalized table, and a bandpass filter with a 200 MHz bandwidth and a 6 GHz center frequency is obtained through the use of a resonant circuit. The dimensions of the transmission lines are determined using theoretical formulas and verified through Matlab files and the MWO-AWR optimization tool. The voltage gain graphs generated demonstrate that the designs created on an FR4 substrate are suitable for use in the IEEE C Band for Wi-Fi-6.Öğe Encryption and Decryption of the Data by Using the Terms of the Lucas Series(2021) Duman, Mehmet; Duman, Merve GüneyThe sequence, whose initial condition is 2 and 1, obtained by summing the two terms preceding it, is called the Lucas sequence. The terms of this series continue as 2, 1, 3, 4, 7, 11, 18, 29, ... respectively. The features of the Lucas sequence have been studied in many projects in the literature and many studies have been done on Lucas series in applied sciences. Cryptology is the science that deals with encrypting data, transferring it securely from one point to another, and converting the encrypted data to the previous one. It includes cryptography and cryptoanalysis. Different encryption-decryption methods have been developed to ensure the security of the data from the past to the present. Some of these are Caesar, Affine, Vigenere and RSA. There are two types of encryption systems in cryptology. The first one is symmetric (secret key) encryption and the another one is asymmetric (public key) encryption. In this study; using the features of the Lucas sequence, studies on cryptology, which deals with the correct encryption, transfer and decryption of data, have been carried out and an example of cryptology algorithm has been given. With Lucas cipher, the letters in the alphabet and the space character are each mapped to the terms of the Lucas sequence. Later, starting from the first term of the Lucas sequence, the encryption was strengthened by adding Lucas terms. As a result, the text to be encrypted has been turned into a symbolic representation of the numbers. Then, the necessary information for deciphering the text which is encrypted with numbers is given.Öğe Frekans Seçici Yüzey Analizi Yöntemiyle Gerçekleştirilmiş 1.35 GHz Frekanslı Bant Durduran Süzgeç Tasarımı(2019) Duman, MehmetElektromanyetik cihazların ve geliştirilen diğer elektronik aygıtların bilişim ve elektronik sektöründe sonyıllarda sağladığı kolaylık ile birlikte insan sağlığına olumsuz etkileri de bulunmaktadır. Bu çalışmada,elektriksel sistemlerden kaynaklanan istenmeyen etkileri, seçilen frekans aralıklarında engellemek veyaazaltmak için frekans seçici yüzey analizi yardımıyla oluşturulan bant durduran süzgeç tasarımıanlatılmaktadır. 1.35 ?????? merkez frekansında çalışan ve 44 ?????? bant genişliğine sahip olan süzgeç,kompozit epoksi plakaların iç kısmında yapılan bir takım değişiklikler ile herhangi bir aktif ya da pasif devreelemanı kullanılmaksızın sadece plaka ile süzgeç işlevini gerçekleştirmektedir. Gerçekleştirilen süzgecinboyutları ayarlanarak cep telefonu, bilgisayar, modem, vb. gibi yayılım yapan ve yan etkileri bulunancihazların, 1.35 ?????? merkez frekansı civarlarında olumsuz etkilerinden kurtulmak mümkündür. Aynı şekilde,yayılım yapan elektronik cihazın, tasarlanan süzgecin bant genişliği boyunca, diğer elektronik aygıtlar ileyapacağı girişim de engellenmiş olacaktır.Öğe High-resolution 96-GHz (3 mm) passive millimeter-wave imaging system and the effect of scanning resolution on images(Spie-Soc Photo-Optical Instrumentation Engineers, 2022) Salman, Alp Oral; Duman, MehmetA high-resolution 96-GHz (3 mm) passive millimeter-wave imaging system is constructed. The system has a 96-GHz radiometric receiver, which is placed on the focal point of a 50-cm diameter parabolic reflector designed and created. A specially written program for the system controls the antenna via control hardware in desired steps by a 2-axis positioner motor. A balance weight has been calculated and mounted to the rear of this parabolic reflector antenna to prevent possible damage to the rotor of the positioner motor due to the antenna's weight. The maximum field of view of the system is 120 deg in azimuth and 90 deg in elevation. The angular scan step can be varied from 0.1 deg to 1 deg. Although the system can shoot 1190 x 890 samples (pixels) images, which is close to the HD quality (1280 x 720 pixels) in the full field of view, the actual resolution of the image is limited by the antenna's beamwidth (BW). Some measurements were performed to investigate the effect of scanning steps on PMMW image quality for different angular scan steps. It is observed that the PMMW image scan with the smallest step gives a detailed image that is the closest to the scene's optical image as expected. Even though the angular scan step angle is less than half of the antenna's BWat Nyquist sampling, it is observed that the image quality still improves due to averaging effect of the received signals giving a better estimated S/N. The resolution and scan step values of our system are compared with that of some systems found in the literature and it is shown that ours has the highest value among them. This system can be used to obtain high-resolution images in remote sensing and other applications. (c) 2022 Society of Photo-Optical Instrumentation Engineers (SPIE)Öğe Issue of the effective dielectric constant for a co-planar patch antenna made with inset technique(Ieee, 2023) Duman, MehmetIn microstrip antenna design, the effective dielectric constant value is different on the feed line or on the patch. The reason for this difference has been demonstrated theoretically and experimentally in this study. The work created in the CST program using the inset technique was carried out on FR4 substrate and measured in the laboratory with Nano-VNA. As a result, the theoretical and simulation values and measurement results are consistent. The antenna can be used in the S band. Examples from the literature and the gap in the literature are given in the introduction; design equations and proof of recalculation for effective dielectric constant are shown in the theoretical calculations, the materials used and the method followed are presented in the method and materials; computer program simulations and laboratory measurements take place in the simulation and measurement section, respectively. Separate headings have been opened to indicate their importance for results, discussion, conclusion and suggestions. One can design a co-planar antenna by following this work.Öğe LNA Design and Implementation for Passive Millimeter Wave Imaging System in Ka Band(Wydawnictwo Sigma-Not Sp Zoo, 2022) Duman, Mehmet; Salman, Alp OralThere are several methods of creating a Passive Millimeter Wave Imaging System (PMMWIS). One of these methods is to use tripod, 2-axis positioner, control unit, the parabolic reflector antenna (PRA) and the radiometric receiver located at the focal point of the PRA. The radiometric receiver, which is the most important part of the system can be divided into parts such as low noise amplifier (LNA), detector, mixer and video amplifier (VA). In this study; LNA will be explained. PMMWIS is an imaging method that emerged as a result of the weakening of the radiation in other systems due to atmospheric effects. In case of working in certain frequency windows (35 GHz, 96 GHz, 220 GHz, ...); the radiation will not be affected by weather events and can be measured. In this study, an LNA has been created for a radiometric receiver that can be operated at Ka-band. Hittite brand HMC1040LP3CE chip from Analog Devices Company, which can theoretically give 23 dB gain in Ka-band has been preferred. The discrete elements and the chip in the circuit are very precisely placed on the board with special solder mixtures using electronic magnifiers, and 2.92 mm connectors are included in the input and output (IO) of the RF line of the circuit. In the last case; the LNA circuit, which was prepared for measurement, was fed with the power supply. It was measured with the help of vector network analyzer (VNA). At last, the LNA working in the Ka-band produced for PMMWIS with a gain value of 19.32 dB at 26.2 GHz center frequency was obtained.Öğe A Novel Approach for Microwave Oven Technology(Ieee, 2023) Duman, MehmetMicrowave ovens incorporate a perforated cover design to enable visualization of the interior while in operation. The heating of food within these ovens is facilitated by electromagnetic (EM) waves, which are generated inside and cannot escape through the cover's perforations, as their diameter is smaller than the wavelength of the EM wave. This study aims to modify the cover design and operating frequency of a microwave oven in a theoretical and simulation environment. The proposed design operates at a frequency of 4 GHz and features a cover with 49 full, 14 half and 1 quartile round holes, each with a diameter of 2 mm. The EM waves are emitted from the upper posterior wall on the right side of the cover (port 1), and only escape through the cover's perforations (port 2) due to the metal covering on all walls. Loose steel material with 1008 properties was utilized for simulation purposes, and open air boundary conditions were applied to the cover's zone while conducting wall boundary conditions were utilized in other sections. The study also analyzed the EM field propagation characteristics and found that a minimum of -164.1 dB was achieved at 3.98 GHz and -163.7 dB at 4 GHz. The results demonstrate the creation of a cap that functions as a band-stopping filter, and the investigation of S parameters, particularly S21. Finally, this study presents a novel microwave oven technology.Öğe Pasif Milimetre Dalga Görüntüleme Sistemi için Radyometrik Alıcının Parabolik Yansıtıcı Antendeki Doğru Konumunun Belirlenmesi(2020) Salman, Alp Oral; Duman, MehmetSavunma ve navigasyon gibi alanlarda, optik ve kızılötesi görüntüleme sistemlerinin sağlıklı çalışamadığı sis,yağmur ve toz gibi görüşü engelleyen çeşitli hava olaylarında, ortamı görüntülemek için, tamamlayıcı sensörolarak Pasif MiliMetre Dalga Görüntüleme Sistemi (PMMDGS) kullanılabilir. Sistem; radyometrik a lıcınınparabolik yansıtıcı anteninin odak noktasında bulunduğu ve bu antenin iki eksende (azimut ve kalkış) çalışan birkonumlandırıcı tarafından taranmasıyla görüntülemenin yapıldığı bir teknolojiye sahiptir. Bir PMMDGS’degörüntülenen ortamdan gelen sinyalin oldukça zayıf olmasından dolayı hem iyi bir kuvvetlendirmenin yapılmasıhem de alıcıdan optimal sinyalin elde edilebilmesi için radyometrik alıcının parabolik yansıtıcı antenin odaknoktasına doğru konumunda yerleştirilmesi büyük bir önem arz etmektedir. Bu çalışmada; PMMDGS’nin anteni,gökyüzü gibi sabit bir görüntüleme noktasına yönlendirilmiş iken radyometrik alıcı, parabolik yansıtıcı antendenbelli mesafelerde kaydırılmış ve optimal sinyalin elde edildiği konum bulunmuştur. Sonuçlar, algılamanınradyometrik alıcıya bağlı olan horn antenin açıklık ucundan değil, bağlantı kısmına yakın bir noktadan olduğunugöstermiştir.Öğe Power Amplifier and Low Noise Amplifier for WLAN Applications(TUBITAK, 2022) Duman, MehmetWireless Local Area Network (WLAN) applications operating at a frequency of 2.45 GHz are a frequently used communication method in transmission tools. The connection functions to send and receive data between access points and smart devices are also fulfilled by WLAN technology. Communication quality in data transfer gains importance for this technology at every stage. Front-end module structures are used to increase such quality affects directly the efficiency. Circuits including power amplifier (PA), low noise amplifier (LNA), antenna and filter are the most significant components that compose front-end structures. In this study, PA and LNA using PW570 gain block & BFP760 RF transistor circuit respectively are proposed. Through the usage of the proposed circuits, there will be considerable improvements in data communication speed and area of coverage, which are among the WLAN performance factors. © 2022, TUBITAK. All rights reserved.Öğe Providing the Moment of the Parabolic Reflector Antenna in the Passive Millimeter Wave Imaging System with the Equilibrium Weights(Springer International Publishing Ag, 2020) Duman, Mehmet; Salman, Alp OralIn foggy, cloudy and rainy weather; for the purpose of radiometric imaging; Passive MilliMeter Wave Imaging System (PMMWIS) was installed with a radiometric receiver operating at a frequency of 96 GHz which is one of the specific frequency windows for passive detection. After the installation of this system, while working, there were contractions in the motor part of the 2-axis positioner with which the parabolic reflector antenna of the PMMWIS. These contractions were mainly during upward system calibration or during normal scan of the system. Therefore, it had become necessary to make balance weights for more convenient operation. In this study; the equilibrium weights were integrated in order to synchronize the moment to the opposite direction of the parabolic reflector antenna. According to the weight and height of the parabolic reflector antenna to be mounted on the system, four different balance weights could be used. The sounds from the gears in the engine of the 2-axis positioner, indicating that the motor was contracted for every degree to be scanned (it could be 0.1 degrees to the resolution) was indicative of the deterioration of the gears in the 2-axis positioner. Consequently; the balance weights were produced and integrated into the system. As a result; the torque of the antenna was achieved and the 2-axis positioner was able to scan the view by means of PMMWIS without any contraction in the azimuth and elevation axes.Öğe RF Power Amplifier for Amateur Radio Applications(Institute of Electrical and Electronics Engineers Inc., 2022) Duman, MehmetThis study includes a power amplifier circuit within AD8353 RF gain block, operating at 433 MHz frequency, providing gain higher than 16 dB and 4th order Chebyshev bandpass filter circuit consisting of lumped elements having 100 MHz bandwidth. The real library data in the Cadence AWR program has been used for the relevant designs suitable for amateur satellite applications operating at an altitude of 600 km and radio communication devices. This useful power amplifier is also applicable for countries such as Portugal and Norway, which implement 5G technology using 450 MHz and its surroundings. © 2022 IEEE.Öğe Theoretical Investigation of Blackbody Radiation for the Passive Millimeterwave Imaging System(Ieee, 2018) Duman, Mehmet; Salman, Alp OralIn a passive millimeter wave imaging (PMMWI), there is no outgoing wave from the antenna of PMMWI system unlike the RAdio Detection And Ranging (RADAR). Antenna is only used to measure incoming waves which are coming from the all things because of being more than 0 Kelvin temperature or being non-blackbody. Radiation of the wall and the glass are different in a building; as a result, the PMMWI system can image the building with a good resolution to distinct the wall and glass. It can also image the gun that is under the cloth thanks to radiation difference. These systems utilize Planck, Wien and Rayleigh-Jeans Theories to view the images which are scanned in azimuth and elevation axis by PMMWI system through its antenna. In this work, the Planck, Wien and Rayleigh-Jeans Theories are analyzed and their formulas are run on MatLab Program with different temperatures for frequency or wave length at x-axis and for spectral radiance at y-axis.Öğe Uplink application circuit for satellite communications(Elsevier Ltd, 2022) Duman, MehmetAmplifiers are of great importance for linear, efficient and stable satellite communication (SatCom). It is necessary to design circuits at different frequencies according to the uplink and downlink applications used in this type of communication. Filtering unnecessary frequencies with a band pass filter (BPF) circuit, amplifying weak signals with a low noise amplifier (LNA), and increasing the power to be transmitted with a power amplifier (PA) are also among the tasks that need to be done. In this study, a design that is valid for uplink services and can be used in SatCom has been made. BPFs, LNA and PA topologies are used together in this proposed circuit. Chips produced by Hittite company were used for LNA and PA. The LNA S21 parameter is approximately 26 dB; the gain has been increased around 48 dB with the PA. The studies were carried out on the AWR tool, between 8 and 20 GHz, especially in the IEEE Ku band (12-18 GHz) which includes uplink frequency windows, 14-14.50 GHz for safe wireless communications. © 2023 Elsevier Ltd. All rights reserved.
