Dr. Maher Khaliel
Institute of Digital Signal Processing, Duisburg-Essen University, 47057, Duisburg, Germany and Benha Faculty of Engineering, Benha University, Egypt
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Academic Career Length
13Years (2014-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications23 October 2017 in IEEE Journal of Radio Frequency Identification
Journal Article
Maher KhalielAEAhmed El-Awamry
Ahmed El-AwamryAMAbdelfattah Fawky Megahed
Abdelfattah Fawky Megahed
TKThomas Kaiser
Thomas Kaiser
This paper presents a novel frequency coded chipless RFID tag, which exploits the backscattered co-polarized and cross-polarized responses from a tag illuminated with a linear polarized wave. Consequently, the tag-ID is configured in two orthogonal planes. The frequency notches are encoded in the co-polarization plane and the re-radiation peaks are encoded in the cross-polarization plane. Therefore, the co/cross-polarizing Notch/Peak modulation scheme presents a novel criterion for maximizing the coding capacity of the chipless RFID systems. Moreover, the cross-polarized response enhances the tag detection in a real environment. The proposed tag and the associated physical modulation scheme are validated using EM simulations and measurements.
Journal Article
JAJahangir Alam
Jahangir AlamMaher KhalielAMAbdelfattah Megahed
Abdelfattah MegahedAEAhmed El-Awamry
Ahmed El-Awamry
Thomas KaiserThis paper focuses on the frequency coded chipless Radio Frequency Identification (RFID) wherein the tag’s information bits are physically encoded by the resonators’ notch position which has an effect on the frequency spectrum of the backscattered or retransmitted signal of the tag. In this regard, the notch analytical model is developed to consider the notch position and quality factor. Besides, the radar cross section (RCS) mathematical representation of the tag is introduced to consider the incident wave’s polarization and orientation angles. Hence, the influences of the incident wave’s orientation and polarization mismatches on the detection performance are quantified. After that, the tag measurement errors and limitations are comprehensively explained. Therefore, approaches to measureing RCS- and retransmission-based tags are introduced. Furthermore, the maximum reading range is theoretically calculated and practically verified considering the Federal Communications Commission (FCC) Ultra Wideband (UWB) regulations. In all simulations and experiments conducted, a mono-static configuration is considered, in which one antenna is utilized for transmission and reception.
Journal Article
Maher KhalielABAman Batra
Aman BatraAMAbdelfattah Megahed
Abdelfattah MegahedThomas KaiserThis paper proposes a novel single-layer, low-profile harmonic transponder to be integrated with the printable diodes based on Si particles. The introduced prototype consists of two bowtie dipoles that are directly matched to the harmonic generation element at a fundamental frequency and also at the corresponding second harmonic frequency. Therefore, the antennas and T-matching parts can be manufactured as separate inlays using a single layer-substrate. Besides the new prototype, the harmonic conversion loss (CL) is theoretically and experimentally investigated. In this regard, the equivalent circuit is driven and utilized to analyze the CL performance with variations in fundamental frequency and input power. The introduced transponder outperforms the state-of-the-art work from the printability, size, and CL point of views.
1 July 2015
Conference Paper
Maher KhalielAEAhmed El-Awamry
Ahmed El-AwamryAFAbdelfattah Fawky
Abdelfattah Fawky
MEMohamed El-Hadidy
Mohamed El-HadidyThomas KaiserThe aim of this work is to introduce a novel tag design enhancing the coding efficiency for the Frequency Coded (FC) chipless RFID system. The proposed approach relies on exploiting the backscattered co/cross-polarized signals from a tag excited with a linear-polarized wave. Consequently, the tag signature is encoded into Notch/Peak (N/P) format in two orthogonal planes. Furthermore, the introduced tag design exhibits narrow resonance bandwidth ensuring best utilization of the operating frequency range and sufficient coding capacity with compact tag size. Hence, 80-bit coding capacity is reached employing physical amplitude On Off-N/P (OO-N/P) modulation and N/P-Position (N/P-P) modulation principles. The presence or absence of a resonator resembles the OO-N/P modulation while the shift in the frequency position imitates the (N/P-P) modulation. In addition, the depolarization property increases the probability of tag detection in a real-world heavily dense multi-path environment. An asymmetry crossed dipole structure is employed to facilitate coding in both divergent polarities separately. The manufactured tags are verified in indoor real-world environment to proof the robustness of the introduced tag design and encoding algorithm. In the full paper, various parameters such as reading range, tag miniaturization and angular stability will be investigated.
Journal Article
AEAhmed El-Awamry
Ahmed El-AwamryFZFeng Zheng
Feng ZhengThomas KaiserMaher KhalielThis paper details the design and implementation of a harmonic frequency-modulated continuous-wave (FMCW) radar system, specialized in detecting harmonic tags and achieving precise range estimation. Operating within the 2.4–2.5 GHz frequency range for the forward channel and 4.8–5.0 GHz for the backward channel, this study delves into the various challenges faced during the system’s realization. These challenges include selecting appropriate components, calibrating the system, processing signals, and integrating the system components. In addition, we introduce a single-layer passive harmonic tag, developed specifically for assessing the system, and provide an in-depth theoretical analysis and simulation results. Notably, the system is characterized by its low power consumption, making it particularly suitable for short-range applications. The system’s efficacy is further validated through experimental evaluations in a real-world indoor environment across multiple tag positions. Our measurements underscore the system’s robust ranging accuracy and its ability to mitigate self-interference, showcasing its significant potential for applications in harmonic tag detection and ranging.
1 March 2018 in International Journal of Microwave and Wireless Technologies
Journal Article
Maher KhalielAEAhmed El-Awamry
Ahmed El-Awamry
AFAbdelfattah Fawky
Abdelfattah Fawky
TKThomas Kaiser
Thomas Kaiser
This work proposes the utilization of a high gain and pencil beam reflectarray (RA) antenna at the reader of the frequency coded (FC) chipless radio-frequency identification (RFID) system to minimize the environmental reflections and increase the reading range. Moreover, the reader antenna should operate over ultra wideband (UWB) range of frequencies to accommodate multiple bits. However, the conventional antenna arrays cannot operate over UWB range of frequencies with high gain and pencil beam characteristics. Therefore, a novel UWB RA antenna dedicated to the chipless RFID reader is developed. The developed RA antenna operates over UWB range of frequencies from 4 to 6GHzto fulfill the requirements of the FC chipless RFID system. Therefore, the antenna is successfully integrated with the FC chipless RFID tags, and a reading range of 1mis achieved.
About Me
received B.Sc. and the M.Sc. degrees in electrical engineering from Benha University in 2007 and 2012, respectively, and a Ph.D. degree in electrical engineering from the Institute of Digital Signal Processing, Duisburg-Essen University in 2016. His Ph.D. research was centered around innovating chipless RFID tags, developing the reader antenna, and integrating innovative approaches to advance reader functionality. He has published a number of journal/conference papers, was nominated for the Best Student Paper Award at the European Conference on Antennas and Propagation (EUCAP 2015 and 2017), and was a co-recipient of several awards, including the Best Paper Award of the 15th IEEE International Conference on Communications Systems (ICCS 2016). Maher was with Benha University as a teaching assistant from 2007 to 2012 and a lecturer from April 2018 to October 2018. He joined the Editorial Board of MDPI's Electronics Journal as a Guest Editor since August 2021, and he also serves as a reviewer for numerous journals such as IEEE Transactions on Microwave Theory and Techniques, IEEE Transactions on Antennas and Propagation, IEEE Journal of Radio Frequency Identification, etc. Dr. Maher has more than 10 years of professional experience at several companies (Vodafone, CST) in the Middle East area, and he is currently a senior developer at ID4us GmbH, Duisburg, Germany, and a post-doctoral researcher at the institute of Digital Signal Processing, Duisburg-Essen University.