Yazar "Althuwayb, Ayman A." seçeneğine göre listele

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    Compact 5 G mmWave vivaldi antenna for vehicular communication
    (Elsevier Inc., 2025) Saleh, Sahar; Saeidi, Tale; Timmons, Nick; Althuwayb, Ayman A.; Razzaz, Faroq
    As a key contribution, this article presents the first successful application of the newly developed Vivaldi Non-uniform Profile Antenna (VNSPA) theory to a Vivaldi Tapered Slot Antenna (VTSA) operating in the 26 GHz band (24.25–27.5 GHz). The proposed design achieves both compactness and simplicity while maintaining high performance. This antenna is a promising candidate for vehicular communication applications, aiming to enhance connectivity, road safety, security, and environmental system control. First, a VTSA with a small volume of 8.1 × 8.3 × 0.813 mm3 is designed, fabricated, and tested, providing S11 value < -11.34 dB at 15.96–28.41 GHz and a maximum realized gain of 6 dBi. Second, a 33 % size reduction of its tapered slot profile (TSP) is obtained by applying the VNSPA theory, resulting in the Vivaldi Non-uniform Slot Antenna (VNSA). Based on this theory, two different non-uniform slot profiles (NSPs) are obtained for VNSA 1 and 2 with final 37 % and 32.55 % volume reduction, respectively, based on parametric studies. VNSA 1 and 2 provide S11 values < -11.6 dB and < -14.3 dB at 16.71 to 27.68 GHz and 17.94 to 27.38 GHz with peak realized gains of 4.6 dBi and 5.15 dBi, respectively. Another key contribution of this research is the on-vehicle analysis of the proposed antenna's applicability for communication. This includes testing the antenna in various positions and demonstrating its capability to radiate in multiple directions, enabling effective communication with other vehicles, pedestrians, roadside units, and mobile networks. Another significant aspect of this research is the calculation of specific absorption rate (SAR), which addresses the effects of electromagnetic radiation on the driver, one back-seat passenger, and pedestrians. The Computer Simulation Technology (CST) software is used to carry out the simulation. © 2025
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    Compact ultra-wide band two element vivaldi non-uniform slot MIMO antenna for body-centric applications
    (Elsevier B.V., 2024) Saleh, Sahar; Saeidi, Tale; Timmons, Nick; Alali, Bader; Razzaz, Faroq; Althuwayb, Ayman A.
    This work presents a novel compact two-port Vivaldi Non-uniform Slot MIMO Antenna (VNSMA) to overcome the challenges of traditional ultra-wideband (UWB) antennas, such as large size, limited bandwidth (BW), high mutual coupling, and suboptimal performance in wearable devices. Designed based on Vivaldi non-uniform slot profile antenna (VNSPA) theory, this antenna offers superior performance metrics and significantly advances wearable antenna technology. The novelty of this work is investigating different positions for the two compact UWB Vivaldi nonuniform Antennas (VNSAs) to get better performance with smaller sizes, wider impedance matching BW, and lower mutual coupling (MC) where side by side at an angle of 180ᵒ is determined to be the best configuration. Detailed parametric studies were performed on this configuration for better performance, where the MC was further reduced by etching the ground plane with a vertical slot between the two antennas and L slots around the Microstrip to Slot (M/S) transition, respectively. Furthermore, BW and gain enhancements were obtained by etching exponential tapered and triangular slots at its two edges. Using the Finite Integration Technique (FIT), Computer Simulation Technology (CST) software is used for the simulations in this work. The VNSMA is tested on a CST Gustav human phantom and gives excellent results with low specific absorption rate (SAR) values at several UWB frequencies. The proposed VNSMA provides good, measured outcomes of S11 < −11.08 dB with wide BW of 12.5 GHz (2.33–14.83 GHz) covering high isolation of −23 dB (for most of frequency band), moderate-high gain of 5.89 dBi, radiation efficiency of 66–90 %, low Envelope Correlation Coefficient (ECC) of 0.002 and high diversity gain (DG) of 9.99 dBi, stable radiation patterns, and average group delay of 1.2 ns. This innovative design, which optimizes antenna positioning and incorporates ground plane modifications, achieves remarkable improvements in BW, which covers multiple bands, including WLAN (2.4–2.485 GHz), X-band (8–12 GHz), and part of Ku band (12–18 GHz). The findings demonstrate the antenna's potential for various high-resolution microwave imaging applications, particularly in medical diagnostics like breast and brain cancer detection, showcasing its impact in wearable technology and healthcare. © 2024 The Authors
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    High-performance UWB Vivaldi antenna on FR4: A cost-effective solution for wearable technologies
    (Elsevier B.V., 2025) Saleh, Sahar; Saeidi, Tale; Timmons, Nick; Alali, Bader; Razzaz, Faroq; Althuwayb, Ayman A.
    This paper introduces a novel Vivaldi Tapered Slot Antenna (VTSA) designed for wearable Ultra-Wideband (UWB) applications, utilizing a cost-effective FR4 substrate with a thickness of 0.8 mm. The proposed design achieves an 18.81 % size reduction (38.3 mm × 27.06 mm × 0.8 mm), a 36.16 % bandwidth (BW) increase, and a 16.63 % gain improvement compared to a VTSA using a Rogers RO4003C substrate (42.9 mm × 28.28 mm × 0.813 mm). The key contributions of this work include the effective use of the affordable FR4 substrate to achieve high performance, improvements in antenna compactness and BW through innovative slot designs, and the enhancement of gain and radiation pattern stability through the addition of directors to the slots. These modifications significantly boost the antenna's performance while maintaining a compact design. The antenna's suitability for wearable applications was validated through testing on flat and curved human phantoms made of skin, fat, and muscle, showing low Specific Absorption Rate (SAR) values across the UWB spectrum, confirming its safety for body-centric use. Measured results include S11 values below -10.56 dB over the 3.66–20.42 GHz range, a peak gain of 8.1 dBi, stable radiation patterns, and an average group delay of 0.83 ns. Simulations using Computer Simulation Technology (CST) were validated by experimental testing, demonstrating the antenna's potential for wearable and body-centric applications. © 2025 The Author(s)
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    Meta Surface-Based Multiband MIMO Antenna for UAV Communications at mm-Wave and Sub-THz Bands
    (Multidisciplinary Digital Publishing Institute (MDPI), 2024) Saeidi, Tale; Saleh, Sahar; Timmons, Nick; Al-Gburi, Ahmed Jamal Abdullah; Karamzadeh, Saeid; Althuwayb, Ayman A.; Rashid, Nasr; Kaaniche, Khaled; Ben Atitallah, Ahmed; Elhamrawy, Osama I.
    Unmanned aerial vehicles (UAVs) need high data rate connectivity, which is achievable through mm-waves and sub-THz bands. The proposed two-port leaky wave MIMO antenna, employing a coplanar proximity technique that combines capacitive and inductive loading, addresses this need. Featuring mesh-like slots and a vertical slot to mitigate open-stopband (OSB) issues, the antenna radiates broadside and bidirectionally. H-shaped slots on a strip enhance port isolation, and a coffee bean metasurface (MTS) boosts radiation efficiency and gain. Simulations and experiments considering various realistic scenarios, each at varying vertical and horizontal distances, show steered beam patterns, circular polarization (CP), and high-gain properties, with a maximum gain of 13.8 dBi, an axial ratio (AR) <2.9, a diversity gain (DG) >9.98 dB, and an envelope correlation coefficient (ECC) <0.003. This design supports drones-to-ground (D2G), drone-to-drone (D2D), and drone-to-satellite (D2S) communications. © 2024 by the authors.
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    A Miniaturized and Highly Sensitive Microwave Sensor Based on CSRR for Characterization of Liquid Materials
    (Mdpi, 2023) Al-Gburi, Ahmed Jamal Abdullah; Zakaria, Zahriladha; Abd Rahman, Norhanani; Althuwayb, Ayman A.; Ibrahim, Imran Mohd; Saeidi, Tale; Dayo, Zaheer Ahmed
    In this work, a miniaturized and highly sensitive microwave sensor based on a complementary split-ring resonator (CSRR) is proposed for the detection of liquid materials. The modeled sensor was designed based on the CSRR structure with triple rings (TRs) and a curve feed for improved measurement sensitivity. The designed sensor oscillates at a single frequency of 2.5 GHz, which is simulated using an Ansys HFSS simulator. The electromagnetic simulation explains the basis of the mode resonance of all two-port resonators. Five variations of the liquid media under tests (MUTs) are simulated and measured. These liquid MUTs are as follows: without a sample (without a tube), air (empty tube), ethanol, methanol, and distilled water (DI). A detailed sensitivity calculation is performed for the resonance band at 2.5 GHz. The MUTs mechanism is performed with a polypropylene tube (PP). The samples of dielectric material are filled into PP tube channels and loaded into the CSRR center hole; the E-fields around the sensor affect the relationship with the liquid MUTs, resulting in a high Q-factor value. The final sensor has a Q-factor value and sensitivity of 520 and 7.032 (MHz)/e(r)) at 2.5 GHz, respectively. Due to the high sensitivity of the presented sensor for characterizing various liquid penetrations, the sensor is also of interest for accurate estimations of solute concentrations in liquid media. Finally, the relationship between the permittivity and Q-factor value at the resonant frequency is derived and investigated. These given results make the presented resonator ideal for the characterization of liquid materials.