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Author

F. Elmegri

Other affiliations: Yarmouk University
Bio: F. Elmegri is an academic researcher from University of Bradford. The author has contributed to research in topics: Antenna measurement & Microstrip antenna. The author has an hindex of 6, co-authored 27 publications receiving 133 citations. Previous affiliations of F. Elmegri include Yarmouk University.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a compact dielectric resonator antenna (DRA) for wideband applications is proposed, which consists of two cylindrical DRA resonators that are asymmetrically located with respect to the center of a rectangular coupling aperture.
Abstract: A compact dielectric resonator antenna (DRA) for wideband applications is proposed. Two cylindrical dielectric resonators that are asymmetrically located with respect to the center of a rectangular coupling aperture are fed through this aperture. By optimizing the design parameters, an impedance bandwidth of about 29%, covering the frequency range from 9.62 to 12.9 GHz, and a gain of 8 dBi are obtained. Design details of the proposed antenna and the results of both simulation and experiment are presented and discussed.

46 citations

Journal ArticleDOI
TL;DR: In this paper, a compact dielectric resonator antenna (DRA) with band-notched characteristics for ultra-wideband applications is presented, which increases the reflection coefficient by 235 dB and reduces the gain by 612 dB.
Abstract: In this paper, a compact dielectric resonator antenna (DRA) with band-notched characteristics for ultra-wideband applications is presented A comprehensive parametric study was carried out using CST Microwave Studio Suite TM 2011 to analyze and optimize the characteristics of the proposed antenna Three shapes for the coupling slot were investigated Simulation results show that the proposed DRA had a −10 dB impedance bandwidth of 23% from 997 GHz to 12558 GHz, and a maximum gain of 723 dBi The antenna had a notched band centered at 1057 GHz, which increased the reflection coefficient by 235 dB, and reduced the gain by 612 dB The optimized designs were verified by experimental tests on fabricated samples

17 citations

Journal ArticleDOI
TL;DR: In this paper, balanced dual-segment cylindrical dielectric antennas with ultra-wideband (UWB) operation were proposed and a T-shaped slot and L-shaped microstrip feeding line was suggested to furnish a balanced coupling mechanism for feeding two DRAs, and the performance of the proposed antenna was analyzed and optimised against the target frequency band.
Abstract: This study reports on balanced dual-segment cylindrical dielectric antennas with ultra-wideband (UWB) operation. A T-shaped slot and L-shaped microstrip feeding line was suggested to furnish a balanced coupling mechanism for feeding two DRAs, and then the performance of the proposed antenna was analysed and optimised against the target frequency band. The proposed antenna was then modified by adding a C-shaped strip to increase the gain. The performances of both balanced antennas were characterised and optimised in terms of antenna reflection coefficient, radiation pattern, and gain. The antennas cover the frequency range from 6.4 to 11.736 GHz, which is 58.7% bandwidth. A maximum gain of 2.66 dB was achieved at a frequency of 7 GHz with the first antenna, with a further 2.25 dB increase in maximum gain attained by adding the C-shaped strip. For validation, prototypes of the two antennas were fabricated and tested. The predicted and measured results showed reasonable agreement and the results confirmed good impedance bandwidth characteristics for UWB operation from both proposed balanced antennas.

15 citations

Journal ArticleDOI
TL;DR: In this paper , the authors present a useful insight into the interaction of electromagnetic fields with biological media that is defined by the heat generation due to induced currents and dielectric loss, and summarise the most common techniques utilised between 1978 and 2021, in terms of the operational frequency spectrum, bandwidth, and SAR values.
Abstract: Employing electromagnetic fields (EMFs) in new wireless communication and sensing technologies has substantially increased the level of human exposure to EMF waves. This paper presents a useful insight into the interaction of electromagnetic fields with biological media that is defined by the heat generation due to induced currents and dielectric loss. The specific absorption rate (SAR) defines the heating amount in a biological medium that is irradiated by an electromagnetic field value. The paper reviews the radio frequency hazards due to the SAR based on various safety standards and organisations, including a detailed investigation of previously published work in terms of modelling and measurements. It also summarises the most common techniques utilised between 1978 and 2021, in terms of the operational frequency spectrum, bandwidth, and SAR values.

11 citations

Journal ArticleDOI
TL;DR: In this paper, two multiband planar printed monopole antennas with an optimized size of 57×37.5×0.8mm3 for mobile/wireless and low-band ultra-wide band (UWB) applications are presented.
Abstract: This study presents two multiband planar printed monopole antennas with an optimised size of 57×37.5×0.8 mm3 for mobile/wireless and low-band ultra-wide band (UWB) applications. Both these antennas are constructed as a chorded crescent-shaped radiator, a feed line and a defected ground plane. The experimental and computed results confirm that one design offers a wide usable impedance bandwidth of 114.3%, with a reflection coefficient |S11|<−10 dB, over 1.5–5.5 GHz. The other incorporates a tapered sickle-shaped slot in the radiator and demonstrates a band-suppression feature giving rejection of the worldwide interoperability for microwave access band (3.4–3.69 GHz) where this is not required. The gains and far-field patterns of the antennas are presented and their group delay over the lower band UWB frequency range is also discussed.

11 citations


Cited by
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Journal ArticleDOI
TL;DR: In this survey, WiFi-based indoor positioning techniques are divided into the active positioning technique and the passive positioning technique based on whether the target carries certain devices.
Abstract: With the rapid development of wireless communication technology, various indoor location-based services (ILBSs) have gradually penetrated into daily life. Although many other methods have been proposed to be applied to ILBS in the past decade, WiFi-based positioning techniques with a wide range of infrastructure have attracted attention in the field of wireless transmission. In this survey, the authors divide WiFi-based indoor positioning techniques into the active positioning technique and the passive positioning technique based on whether the target carries certain devices. After reviewing a large number of excellent papers in the related field, the authors make a detailed summary of these two types of positioning techniques. In addition, they also analyse the challenges and future development trends in the current technological environment.

116 citations

Journal ArticleDOI
TL;DR: This work aims to study recent indoor localization technologies and systems based on various fingerprints, which use machine learning and intelligent algorithms, and presents the architecture of intelligent localization, which shows how to make localization become more “smart” by advanced techniques.
Abstract: With the rapid development of Internet of Things (IoT) technology, location-based services have been widely applied in the construction of smart cities. Satellite-based location services have been utilized in outdoor environments, but they are not suitable for indoor technology due to the absence of global positioning system (GPS) signal. Therefore, many indoor localization technologies and systems have emerged by utilizing many other signals. In particular, fingerprinting localization has recently garnered attention because its promising performance. In this work, we aim to study recent indoor localization technologies and systems based on various fingerprints, which use machine learning and intelligent algorithms. We also present the architecture of intelligent localization. The development of indoor localization technology should have the ability of self-adaptation and self-learning in the future. And the architecture shows how to make localization become more “smart” by advanced techniques. The state-of-the-art localization systems’ working principles are summarized and compared in terms of their localization accuracy, latency, energy consumption, complexity, and robustness. We also discuss the challenges of existing indoor localization technologies, potential solutions to these challenges, and possible improvement measures.

88 citations

Journal ArticleDOI
TL;DR: An inclusive survey on key indoor technologies and techniques is carried out with to view to explore their various benefits, limitations, and areas for improvement, and advocates hybridization of technologies as an effective approach to achieve reliable IoT-based indoor systems.

88 citations

Journal ArticleDOI
TL;DR: A review paper concerning wide-band and ultra-wideband (UWB) antennas used for wireless communication purposes in terms of the materials as well as a numerical analysis is presented.
Abstract: A review paper concerning wide-band and ultra-wideband (UWB) antennas used for wireless communication purposes in terms of the materials as well as a numerical analysis is presented. These antennas which are taken into account are listed as wide-band microstrip antenna, wide-band monopole antenna over a plate, wide-slot UWB antenna, stacked patch UWB antenna, taper slot (TSA) UWB antenna, metamaterial (MTM) structure UWB antennas, elliptical printed monopole UWB antenna, and flexible wearable UWB antenna. The antennas’ performance is compared based on their size and how they can be applicable for portable communication device applications. This review paper furnishes a proper direction to select varieties of figures in terms of impedance bandwidth, gain, directivity, dimensions, time domain characteristics, and materials affecting these antenna’s characteristics.

63 citations

Journal ArticleDOI
TL;DR: A simple, the novel ambient HAR framework using the multivariate Gaussian is proposed and offers pervasive sensing environment for elderly, disabled, and carers and suits well for the single and multi-dwelling environment.
Abstract: Human activity recognition (HAR) from sensor readings has proved to be an effective approach in pervasive computing for smart healthcare. Recent approaches in ambient assisted living (AAL) within the home or community setting offers people the prospect of independent care and improved quality of living. However, most of the available AAL systems are limited by several factors including the system complexity and computational cost. In this paper, a simple, the novel ambient HAR framework using the multivariate Gaussian is proposed. The classification framework augments prior information from passive RFID tags to obtain more detailed activity profiling. The proposed algorithm based on the multivariate Gaussian via maximum likelihood estimation is used to learn the features of the human activity model. The twelve sequential and concurrent experimental evaluations are conducted in a mock apartment environment. The sampled activities are predicted using a new dataset of the same activity and high prediction accuracy established. The proposed framework suits well for the single and multi-dwelling environment and offers pervasive sensing environment for elderly, disabled, and carers.

55 citations