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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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    Enhancing connectivity/mobility in WBAN applications through detachable wearable multi-band MIMO antenna
    (Institute of Physics, 2024) Saeidi, Tale; Saleh, Sahar; Timmons, Nick; Karamzadeh, Saeid; Al-Gburi, Ahmed Jamal Abdullah; Razzaz, Faroq
    The connectivity and mobility of a miniaturized multi-band four-port textile leaky wave multiple-input multiple-output (MIMO) antenna designed on a layer of denim (ϵr = 1.6, tanδ = 0.006) is enhanced by integrating it with two detachable spiral buttons designed on circular PTFE substrate (ϵr = 2.1, tanδ = 0.001). The connectivity and mobility enhancement of the proposed antenna is evaluated in terms of radiation and diversity parameters. Nested hexagonal split rings behind the buttons, U-shaped slots on textiles, a comb-shaped neutralization network, and an aperture-coupled feed technique are utilized. The unique structure of the buttons on a rigid substrate and the leaky wave antenna on the textile and their integration, the periodic nested elliptical and circular split ring resonators (CSRRs) slots on the aperture coupled to ground, are to expand the connectivity and mobility of the proposed MIMO antenna by offering multiple bands, higher isolation, broadside radiation, and low specific absorption rate (SAR). The leaky wave and button antennas have dimensions of 40 × 30 × 1 mm3 and a diameter of only 13 mm, respectively. The operational bands are 0.86-2.75 GHz, 2.9-4.85 GHz, 5.75-6.15 GHz, and 8-9.85 GHz, covering the L, C, S, and X bands. Additionally, diversity performance is evaluated by defining the envelope correlation coefficient (ECC), diversity gain (DG), Channel Capacity Loss (CCL), and mean effective gain (MEG). The simulation and measurement findings are in good agreement. Following that, it offers a maximum gain of 8.25 dBi, low SAR (<0.05), an ECC below 0.05, DG above 9.85 dB, CCL< 0.25 bits/s/Hz, MEG <−3 dB, Circular polarization (CP), and strong isolation (>22 dB) between every two ports. These features make the proposed antenna an ideal option for MIMO communications and suitable for wireless local area network (WLAN) and fifth-generation (5G) communications. © 2024 IOP Publishing Ltd.
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    Enhancing connectivity/mobility in WBAN applications through detachable wearable multi-band MIMO antenna
    (IOP publishing, 2024) Saeidi, Tale; Saleh, Sahar; Timmons, Nick; Karamzadeh, Saeid; Al-Gburi, Ahmed Jamal Abdullah; Razzaz, Faroq
    The connectivity and mobility of a miniaturized multi-band four-port textile leaky wave multiple-input multiple-output (MIMO) antenna designed on a layer of denim (epsilon(r) = 1.6, tan delta = 0.006) is enhanced by integrating it with two detachable spiral buttons designed on circular PTFE substrate (epsilon(r) = 2.1, tan delta = 0.001). The connectivity and mobility enhancement of the proposed antenna is evaluated in terms of radiation and diversity parameters. Nested hexagonal split rings behind the buttons, U-shaped slots on textiles, a comb-shaped neutralization network, and an aperture-coupled feed technique are utilized. The unique structure of the buttons on a rigid substrate and the leaky wave antenna on the textile and their integration, the periodic nested elliptical and circular split ring resonators (CSRRs) slots on the aperture coupled to ground, are to expand the connectivity and mobility of the proposed MIMO antenna by offering multiple bands, higher isolation, broadside radiation, and low specific absorption rate (SAR). The leaky wave and button antennas have dimensions of 40 x 30 x 1 mm(3) and a diameter of only 13 mm, respectively. The operational bands are 0.86-2.75 GHz, 2.9-4.85 GHz, 5.75-6.15 GHz, and 8-9.85 GHz, covering the L, C, S, and X bands. Additionally, diversity performance is evaluated by defining the envelope correlation coefficient (ECC), diversity gain (DG), Channel Capacity Loss (CCL), and mean effective gain (MEG). The simulation and measurement findings are in good agreement. Following that, it offers a maximum gain of 8.25 dBi, low SAR (<0.05), an ECC below 0.05, DG above 9.85 dB, CCL< 0.25 bits/s/Hz, MEG <-3 dB, Circular polarization (CP), and strong isolation (>22 dB) between every two ports. These features make the proposed antenna an ideal option for MIMO communications and suitable for wireless local area network (WLAN) and fifth-generation (5G) communications.
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    High gain multi-band circularly polarized wearable leaky wave zipper MIMO antenna
    (Cell press, 2024) Saeidi, Tale; Saleh, Sahar; Mahmood, Sarmad Nozad; Timmons, Nick; Al-Gburi, Ahmed Jamal Abdullah; Karamzadeh, Saeid; Razzaz, Faroq
    A miniaturized, multi-band, four-port wearable Multiple Input Multiple Output (MIMO) antenna is proposed, which contains a leaky wave textile antenna (LWTA) on denim (epsilon(r) = 1.6, tan delta = 0.006) as substrate and Shieldit Super Fabric as conductor textile. The concept in this work involves incorporating the metal and plastic zipper into the garment to function as an antenna worn on the body. Simulations and measurements have been conducted to explore this idea. The LWTA has dimensions of 40 x 30 x 1 mm(3). Every two ports are separated by a zipper with two different kinds of materials: Acetal Polymer Plastic (APP) and 90 % brass to improve the isolation, gain, and Impedance bandwidth. The antenna operates in the frequency ranges covering the L, C, S, and X bands. Additionally, diversity performance is evaluated using the Envelope Correlation Coefficient (ECC) and diversity gain (DG). Simulation and measurement findings agree well, with a maximum gain of 12.15 dBi, low Specific Absorption Rate (SAR) based on the standards, DG greater than 9.65 dB, circular polarization (CP), and strong isolation (<-23 dB) between each port. Since the antenna's characteristics do not change significantly under bending and when the zipper is opened, the proposed antenna is a viable candidate for body-centric wireless communications on the battlefield. For example, it can facilitate communication covering wireless local area network (WLAN) and fifth-generation (5G) communications.
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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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    Simple compact UWB vivaldi antenna arrays for breast cancer detection
    (MDPI, 2024) Saleh, Sahar; Saeidi, Tale; Timmons, Nick
    In this study, at ultra-wideband (UWB) frequency band (3.1-10.6 GHz), we propose the use of compact 2:1 and 3:1 nonuniform transmission line Wilkinson power dividers (NTL WPDs) as feeding networks for simple 2 x 1 linear UWB Vivaldi tapered and nonuniform slot antenna (VTSA and VNSA) arrays. The 2:1 and 3:1 tapered transmission line (TTL) WPDs are designed and tested in this work as benchmarks for NTL WPDs. The VTSA array provides measured S-11 < -10.28 dB at 2.42-11.52 GHz, with a maximum gain of 8.61 dBi, which is 24.39% higher than the single element. Using the VNSA array, we achieve 52% compactness and 6.76% bandwidth enhancement, with good measured results of S-11 < -10.2 dB at 3.24-13 GHz and 15.11% improved gain (8.14 dBi) compared to the VNSA single element. The findings show that the NTL and Vivaldi nonuniform slot profile antenna (VNSPA) theories are successful at reducing the size of the UWB WPD and VTSA without sacrificing performance. They also emphasize the Vivaldi antenna's compatibility with other circuits. These compact arrays are ideal for high-resolution medical applications like breast cancer detection (BCD) because of their high gain, wide bandwidth, directive stable radiation patterns, and low specific absorption rate (SAR). A simple BCD simulation scenario is addressed in this work. Detailed parametric studies are performed on the two arrays for impedance-matching enhancement. The computer simulation technology (CST) software is used for the simulation. Hardware measurement results prove the validity of the proposed arrays.
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    Ultra-wideband (UWB) antennas for breast cancer detection with microwave imaging: A review
    (Elsevier B.V., 2025) Saeidi, Tale; Mahmood, Sarmad Nozad; Saleh, Sahar; Timmons, Nick; Al-Gburi, Ahmed Jamal Abdullah; Razzaz, Faroq
    In recent years, microwave imaging has attracted much attention and offers several advantages over existing imaging systems. It allows for a thorough examination of biological tissues, making it possible to identify changes in their shape and pinpoint their exact locations. One exciting development in this field is ultra-wideband (UWB) microwave imaging, which delivers superior results while using radiation that is not harmful. Antennas are a crucial part of UWB systems and require careful optimization, especially considering their proximity to the human body. Various factors need to be considered when designing antennas, including the choice of materials and dimensions, operational bandwidth, the impact of the human body on antenna performance, and the dynamics of short-pulse propagation. Recent research has focused on improving electromagnetic sensors used in these systems, whether as standalone units or as part of antenna arrays. This paper aims to comprehensively review significant advancements in high-performance UWB antenna sensors used in microwave imaging systems utilized for breast cancer detection. © 2025 The Authors