Lokman Kuzu

Bio: Lokman Kuzu is an academic researcher from Scientific and Technological Research Council of Turkey. The author has contributed to research in topics: Antenna (radio) & Frequency domain. The author has an hindex of 4, co-authored 16 publications receiving 83 citations. Previous affiliations of Lokman Kuzu include Syracuse University.

Electromagnetic scattering from arbitrarily shaped chiral objects using the finite difference frequency domain method

Abstract: In this paper, finite difference frequency domain (FDFD) formulation has been developed for the analysis of electromagnetic wave interaction with chiral materials, and the validity of the formulation for three dimensional scattering problems has been confirmed by comparing the numerical results to exact or other numerical solutions. The influences of the chirality on the scattered field components are investigated. Numerical results for bistatic radar cross section (RCS) are presented and compared to reference solutions and it is found that the proposed FDFD method shows good agreement. It is realized that the presented method is relatively easy to program and can be applied to a wide variety of problems of complex and composite structures efficiently.

An ultra-wide band low-SAR flexible metasurface-enabled antenna for WBAN applications

Abstract: In this study, an ultra-wideband low-specific absorption rate (SAR) flexible metasurface-enabled wearable antenna is proposed for wireless body area network applications. The antenna and metamaterial (MM) structure were designed and analyzed using a commercial electromagnetic simulation software program which uses a finite integration technique solver. The antenna is designed and fabricated on a jeans textile substrate in the size of 58 × 80 × 1 mm3. Moreover, MM reflector was designed on a felt textile substrate to reduce the SAR effect of the antenna and to increase the antenna performance (such as impedance matching, radiation pattern, and realized gain) parameters. Designed and fabricated antenna parameters and the SAR value results with and without MM are investigated. The simulated peak SAR values when the antenna with MM is placed on the body model are 0.86, 0.198, and 0.103 W/kg at frequencies of 4 GHz, 7 GHz, and 10 GHz, respectively, for 10 g of tissue. The simulated peak SAR value of the antenna with MM is also reduced by a percentage of 97, compared to the simulated peak SAR value of the antenna without MM. The peak SAR values of the antenna were less than the European safety limit of 2 W/kg for 10 g of tissue when the MM was used as an isolator. Furthermore, the simulated peak realized gain value of the antenna with the MM was increased by 98% (from 4.6 to 9.1 dB) compared to the simulated peak realized gain value of the antenna without MM. Simulation and measurement results showed that performance characteristics and peak SAR values of the proposed antenna were suitable and safe for wearable technologies.

An antenna array for Ku band satellite reception

Abstract: A Ku-band antenna is designed in this study. The wide-band antenna is made of a multilayer planar slot array operating at 11.725 GHz center frequency for satellite communication purposes. The simulation results are presented in this paper.

Reliability analysis of TUSAT satellite communication payload

Abstract: A communication satellite consists of subsystems which are functioning together to form a whole system. All subsystems consist of thousands of components and there is no possibility of repair once the satellite launched into orbit. Therefore, the necessity of high reliability becomes a rule rather than an exception. TUSAT (Turkish National Communication Satellite) is planned to have both C and Ku band payloads operating in geostationary orbit. This paper presents the reliability analysis of its payload as support to the overall satellite level system design. The paper includes payload redundancy schemes and reliability budgets based on the main subsystem assumptions.

A planar Ku band antenna for satellite communications

Abstract: In this study a planar Ku band antenna is designed and built for satellite communications especially to receive TV signals in Turkey. This paper summarizes the design and manufacturing phases of the study and demonstrates the simulation results of the prototype antenna.

An Inclusive Survey on Array Antenna Design for Millimeter-Wave Communications

Abstract: The enormous growth of wireless data traffic in recent years has made the millimeter-wave (mm-wave) technology as a good fit for high-speed communication systems. Extensive works are continuing from the device to system, to the radio architecture, to the network to support the communication in mm-wave frequency ranges. To support this extensive high data rate, beam forming is found to be the key-enabling technology. Hence, an array antenna design is an extremely important issue. The beam-forming arrays are chosen to achieve the desired link capacity considering the high path loss and atmospheric loss at mm-wave frequencies and also to increase the coverage of the mm-wave communication system. There are diverse design challenges of the array due to the small size, use of large numbers of antennas in close vicinity, integration with radio-frequency (RF) front ends, hardware constraints, and so on. This paper focuses on the evolution and development of mm-wave array antenna and its implementation for wireless communication and numerous other related areas. The scope of the discussion is extended on the reported works in every sphere of mm-wave antenna array design, including the selection of antenna elements, array configurations, feed mechanism, integration with front-end circuitry to understand the effects on system performance, and the underlying reason of it. The new design aspects and research directions are unfolded as a result of this discussion.

An Array Antenna for Both Long- and Medium-Range 77 GHz Automotive Radar Applications

Abstract: A novel array antenna with a flat-shoulder shaped radiation pattern is proposed as the transmitting antenna for 77 GHz automotive radar application. When it is used in an automotive radar comprising one transmitter and multiple identical receivers, it can meet the demands of both long-range and medium-range detections without switching the operation mode back and forth between the long-range radar scenario and the medium-range radar scenario. The proposed antenna concept is fully introduced to explain its mechanism. An unconventional array was synthesized to achieve the desired flat-shoulder shaped radiation pattern. Prototype of the proposed array antenna was also designed according to the array synthesis result, which consists of several linear series-fed patch arrays and a substrate-integrated waveguide power and phase distributing network. Fabrication and measurement of the prototype array antenna were completed, showing a good agreement between the measured data and the synthesized as well as the simulation results, thereby validating the design.

Design and analysis of low profile and low SAR full-textile UWB wearable antenna with metamaterial for WBAN applications

Abstract: In this paper, a low-profile wearable antenna with metamaterial (MM) for wireless body area network (WBAN) applications is presented. The designed antenna with MM operates in the ultra-wideband (UWB) between 4.55 and 13 GHz and it has a thickness of 4.68 mm. To the best of our knowledge, it is the lowest thickness reported in the literature for UWB antennas with MM. The proposed is designed and manufactured using fully flexible textiles. The designed antenna was simulated in free space and on the human body model. Simulation results show that gain, directionality, and front-to-back ratio of the antenna increase considerably with the placement of the MM. Also, in simulations, it is found that the specific absorption rate (SAR) values for the designed antenna reduce by 98.3% when MM is used. These SAR values calculated for the designed antenna with MM are well below the limits defined in European standards. The designed antenna and metamaterials were manufactured, too, and scattering parameters were measured. Measurement results are in good agreement with the results found in the simulations. It shows that the proposed antenna is very suitable for use in WBAN applications due to its low thickness, having low SAR, and UWB operation.

ON-OFF Body Ultra-Wideband (UWB) Antenna for Wireless Body Area Networks (WBAN): A Review

Abstract: Ultra-wideband (UWB) technology can offer broad capacity, short-range communications at a relatively low level of energy usage, which is very desirable for wireless body area networks (WBANs). The involvement of the human body in such a device poses immense difficulties for both the architecture of the wearable antenna and the broadcast model. Initially, the bonding between the wearable antenna and the human body should also be acknowledged in the early stages of the design, so that both the potentially degrading output of the antenna as a consequence of the body and the possibility of exposure for the body may be handled. Next, the transmission path in WBAN is affected by the constant activity of the human body, leading to the time-varying dispersion of electromagnetic waves. Few researchers were interested in this field, and some substantial progress has recently been considered. On the other hand, this paper covered both wearable and Non-wearable UWB antenna designs and applications with respect to their substrate characteristics. Finally, this review prospectively exposes the upgraded developments of (ON-OFF) body antennas in the area of wearable and Non-wearable UWB and their implementations in the WBAN device and aims to evaluate the latest design features that inspire the performance of the antennas.