Elektrik-Elektronik Mühendisliği
https://hdl.handle.net/20.500.12508/41
Electrical Electronic Engineering2024-03-29T10:50:24ZA Bandpass Frequency Selective Surface Filter for Earth Observation Satellite and Radar Applications
https://hdl.handle.net/20.500.12508/3039
A Bandpass Frequency Selective Surface Filter for Earth Observation Satellite and Radar Applications
Altıntaş, Olcay
In this paper, a bandpass frequency selective surface filter has been suggested for the satellite and radar
applications at X band frequency regime. The study has been conducted both numerically and
experimentally in a wide range frequency band between 2 GHz and 14 GHz. 2 GHz of 3 dB bandwidth
between 7.3 GHz and 9.3 GHz has been obtained. The proposed structure has the polarization insensitive
characteristic. It also has angular stability with the incident angle ranges from 0° to 60° with very small
frequency deviations both TE and TM polarization modes. The prototype of the FSS structure is
composed of 20x20 unit cells in a dimension of 18cm x 18 cm. The experimental studies have been
conducted by using Agilent PNA-L vector network analyzer with two horn antennas. The bandpass filter
can be effectively used in many satellite and radar systems as an antenna radome to prevent noises and to
reject unwanted frequency bands; Bu makalede, X bant frekans rejiminde uydu ve radar uygulamaları için bir bant geçiren frekans seçici
yüzey filtresi önerilmiştir. Çalışma 2 GHz ile 14 GHz arasındaki geniş bir frekans bandında hem sayısal
hem de deneysel olarak gerçekleştirilmiştir. 7.3 GHz ile 9.3 GHz arasında 2 GHz 3 dB bant genişliği elde
edilmiştir. Önerilen yapı polarizasyona duyarsız özelliğe sahiptir. Ayrıca, hem TE hem de TM
polarizasyon modlarında çok küçük frekans sapmaları ile 0° ila 60° arası geliş açısı aralıklarıyla açısal
kararlılığa sahiptir. FSS yapısının prototipi 18cm x 18cm boyutlarında 20x20 birim hücrelerden
oluşmaktadır. Deneysel çalışmalar Agilent PNA-L vektör ağ analizörü ve iki huni anten kullanılarak gerçekleştirilmiştir. Bant geçiren filtre, gürültüleri önlemek ve istenmeyen frekans bantlarını reddetmek
için bir anten radomu olarak birçok uydu ve radar sisteminde etkin bir şekilde kullanılabilir.
2021-01-01T00:00:00ZAn easy-to-produce HIS-based MIMO radio altimeter antenna design for aircraft
https://hdl.handle.net/20.500.12508/3028
An easy-to-produce HIS-based MIMO radio altimeter antenna design for aircraft
Kiriş, Serap; Karaaslan, Muharrem
PurposeThe purpose of this study is to design a radio altimeter antenna whose production process is facilitated and can work with multiple-input multiple-output (MIMO) properties to provide space gain on the aircraft.Design/methodology/approachTo create an easy-to-produce MIMO, a two-storied structure consisting of a reflector and a top antenna was designed. The dimensions of the reflector were prevented to get smaller to supply easy production. The unit cell nearly with the same dimensions of a lower frequency was protected through the original cell design. The co-planar structure with the use of a via connection was modified and a structure was achieved with no need to via for easy production, too. Finally, the antennas were placed side by side and the distance between them was optimized to achieve a MIMO operation.FindingsAs a result, an easy-to-produce, compact and successful radio altimeter antenna was obtained with high antenna parameters such as 10.14 dBi gain and 10.55 dBi directivity, and the conical pattern along with proper MIMO features, through original reflector surface and top antenna system.Originality/valueSince radio altimeter antennas require high radiation properties, the microstrip antenna structure is generally used in literature. This paper contributes by presenting the radio altimeter application with antenna-reflective structure participation. The technical solutions were developed during the design, focusing on an easy manufacturing process for both the reflective surface and the upper antenna. Also, the combination of International Telecommunication Union's recommended features that require high antenna properties was achieved, which is challenging to reach. In addition, by operating the antenna as a successful MIMO, two goals of easy production and space gain on aircraft have been attained at the same time
2023-01-01T00:00:00ZOptimal design of transmitarray antennas via low-cost surrogate modelling
https://hdl.handle.net/20.500.12508/2995
Optimal design of transmitarray antennas via low-cost surrogate modelling
Belen, Mehmet Ali; Çalışkan, Alper; Koziel, Slawomir; Pietrenko-Dabrowska, Anna; Mahouti, Peyman
Over the recent years, reflectarrays and transmitarrays have been drawing a considerable attention due to their attractive features, including a possibility of realizing high gain and pencil-like radiation patterns without the employment of complex feeding networks. Among the two, transmitarrays seem to be superior over reflectarrays in terms of achieving high radiation efficiency without the feed blockage. Notwithstanding, the design process of transmitarrays is more intricate due to the necessity of manipulating both the transmission phase and magnitude of its unit elements. For reliability, the design process has to be conducted at the level of full-wave electromagnetic models, which makes direct optimization prohibitive. The most widely used workaround is to employ surrogate modeling techniques to construct fast representations of the unit elements, yet the initial model setup cost is typically high and includes acquisition of thousands of training data points. In this paper, we propose a novel approach to cost-efficient design of transmitarrays. It is based on artificial-intelligence-enabled data-driven surrogates, which can be constructed using only a few hundreds of training data samples, while exhibiting the predictive power sufficient for reliable design. Our methodology is demonstrated by re-using the presented surrogate for the design of high-performance transmitarrays operating at various frequency ranges of 8–14 GHz, 22–28 GHz, and 28–36 GHz.
2023-01-01T00:00:00ZDesign and Characterization of a Compact Four-Element Microstrip Array Antenna for WiFi-5/6 Routers
https://hdl.handle.net/20.500.12508/2975
Design and Characterization of a Compact Four-Element Microstrip Array Antenna for WiFi-5/6 Routers
Paul, Liton Chandra; Ankan, Sarker Saleh Ahmed; Rani, Tithi; Jim, Md. Tanvir Rahman; Karaaslan, Muharrem; Shezan, S. Arefin; Wang, Lulu
The WiFi-5 band was the most popular WiFi band until the Federal Communications Commission (FCC) announced a new spectrum of 6 GHz WiFi (5.925-7.125 GHz) for unlicensed users. Our proposed work is about to cover both the 5 GHz and 6 GHz WiFi bands. These two bands have a great impact in the wireless communication field. A low-loss Rogers RT 5880 material is used as the substrate layer, which helps us to make the antenna compact (23x40x0.79 mm(3)) keeping a good performance profile over the latest high-speed WiFi-5/6 band. The proposed antenna covers a huge bandwidth (simulated BW: 2.85 GHz ranging from 4.50 to 7.35 GHz and measured BW: 2.83 GHz ranging from 4.50 to 7.33 GHz), which can be used for the latest WiFi-5 and WiFi-6 routers. The antenna also has omnidirectional properties. Besides that, the gain and directivity of the antenna are quite good, and the measured results buttress the simulated results. The presented different detail parametric studies indicate the antenna's optimization level, which is excellent. The minimum values of reflection coefficient and voltage standing wave ratio make it a compatible candidate for the implementation of high-speed WiFi-5/6 routers.
2023-01-01T00:00:00Z