
Diaa E. Fawzyİzmir University of Economics · Aerospace Engineering
Diaa E. Fawzy
PhD
About
97
Publications
10,944
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624
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Introduction
Our current research is focused on the development of mm-wave-based system components for 5G and 6G technologies. These system components include metamaterial absorbers/reflectors, antennas, filters, amplifiers, and power dividers. At the same time, we are developing theoretical simulation models based on magnetohydrodynamic waves in an attempt to understand the non-radiating heating of the stellar chromospheres.
Education
January 1997 - February 2001
Publications
Publications (97)
The aim of the current study is the computation of wave energy fluxes for longitudinal tube
waves generated in the convection zone of the chromospherically active star � Eridani. In our
models, we employ a modified theory of turbulence together with the magnetohydrodynamic
equations in a time-dependent setting. The wave generation mechanism is given...
A new broadband phased array antenna with wide-scan and high-gain beam-scanning are desirable to meet the requirements of future cellular networks. This paper discusses the characteristics of a new beam-steerable array design having broad bandwidth for 5G communications. The discussion is focused on smartphones, due to their small size and complexi...
This paper is devoted to design and implementation
of multi-band textile based Metamaterial absorber operating at
K and Ku bands to be deployed in energy harvesting system.
The unit cell of the absorber comprises a ground plane of
copper annealed, Felt textile and top ground layer with etched
Jerusalem cross surrounded with etched square ring. It p...
This paper introduces a 4-port MIMO slot antenna system with dual notched bands, which is designed for future wireless communications. The antenna structure consists of four modified U-shaped radiation stubs with a shared ground plane, arranged in a planar form. The results demonstrate that the antenna operates effectively across frequencies rangin...
This study presents new prediction models of the 11-year solar activity cycles (SC) 25 and 26 based on multiple activity indicator parameters. The developed models are based on the use of Nonlinear Autoregressive Exogenous (NARX) Neural Network approach. The training period of the NARX model is from July 1749 to December 2019. The considered activi...
This study presents a new circular compact Ultra Wide-Band (UWB) substrate integrated gap waveguide (SIGW) based 3 dB hybrid coupler for Ku band applications. The coupling section is a circular structure with an elliptic slot and additional via to achieve equal-power division in two ports and isolation in the 4th port. To optimize the design parame...
We examine the acoustic and magnetic energy generation and propagation in \(\beta \) Hydri (G2 IV). The underlying motivation for this work is based on the solar, stellar, and galactic relevance of \(\beta \) Hyi (a star in the Southern hemisphere), which is readily understood as a prime example and proxy of the future Sun – thus allowing assessmen...
This study presents a new 4 x 1 rectangular slot
antenna array based on ridge gap waveguide (RGW) technology
for the use of D-band applications. The operating frequency of
the proposed array antenna is 140.9 - 157.7 GHz. The Finite
Integration Time-Domain (FITD) method is used to optimize the
design parameters. Four rectangular slots are placed sid...
We examine the acoustic and magnetic energy generation and propagation in β Hydri (G2 IV). The underlying motivation for this work is based on the solar, stellar, and galactic relevance of β Hyi (a star in the Southern hemisphere), which is readily understood as a prime example and proxy of the future Sun --- thus allowing assessments and analyses...
We present results about the decrease of stellar activity for stars like the Sun evolving toward the subgiant stage. Specifically, we examine two-component chromosphere models (acoustic and magnetic) for β Hydri (G2 IV) based on detailed time-dependent simulations while focusing on Ca ii emission. We convey models for two different photospheric mag...
This paper presents a graphene-based antenna array for terahertz (THz) applications. The suggested antenna array has four radiating square shaped patches fed by a coplanar waveguide (CPW) technique. The proposed antenna array operates at the three frequencies with operational bandwidths of 1.173–1.210 THz (at 1.19 THz), 1.270–1.320 THz (at 1.3 GHz)...
This work proposes an ultra-wideband Metamaterial (MM) absorber for smart electronic textile (etextile) applications. The design is based on a novel cell geometry composed of two combined letter patches (A&S) printed on a grounded textile substrate. This unit cell geometry is specifically developed and optimized for millimeter-wave (mm-wave) applic...
This letter describes a dual-band antenna for energy harvesting applications at 3.5 GHz and 5.8 GHz utilizing a multi-objective Genetic Algorithm (GA). An optimized Defected Ground Structure (DGS) has been etched in the patch antenna’s ground to achieve a dual-band response. Moreover, the GA allows obtaining a maximum gain in both frequency bands....
In this paper, a bi-directional coupler based on substrate integrated gap waveguide (SIGW) is presented for Ku-band applications. The proposed coupler is considered to be the first bi-directional coupler that is realized using gap waveguide technology. It operates at frequency band of 14-17 GHz. The quasi-transverse electromagnetic (Q-TEM) SIGW bas...
This study presents the development of a one-layer symmetrical Metamaterial Absorber (MMA) for millimeter-wave (mm-wave) applications. The target is to enhance the narrow band behavior and to achieve ultra-wideband with high absorptivity rates. The design is based on octagonal shaped cut rings and octagonal patches printed on grounded rigid substra...
This paper proposes a novel design of ultra-thin, miniature metamaterial (MM) - based ultra-wideband absorber which is aiming for 5G millimeter-waves and Ka-band applications. The unit cell is designed by combining two letters (H&S) and side patches for the generation of multi-resonance bands and printed on a grounded dielectric of Rogers RT5880 ma...
In this paper, a triple-band inverted microstrip Ridge Gap Waveguide (RGW) filter is designed using a double octagonal ring resonator (RR) with corner cuts. The design parameters are optimized using the Finite Difference Time Domain (FDTD) method (CST studio simulator). The filter is implemented on Rogers RT5880 (εr =2.2, thickness of 0.787 mm and...
This work presents a state-of-the-art development of an ultrawide absorber for wearable smart electronic textile applications. The design is based on a novel cell geometry that is previously developed and applied for RF energy harvesting applications. Different textile types were considered in this study, namely, Felt, Denim and Polyester and the a...
Güneş Aktivite Çevrimlerini (GAC) tahmin etmek; Dünya yörüngesindeki uzay araçlarının güvenliği, iletişim ağları ve genel olarak yaşam üzerindeki olumsuz etkileri nedeniyle önemli hale gelmiştir. Bu çalışmada, 25. GAC tahmini için yaklaşık3246 adet 13 aylık ortalama Güneş Lekesi Sayısı’ndan (GLS) (Temmuz 1749 - Aralık 2019 arasında) oluşan büyük bi...
A novel circular reconfigurable metasurface (MS) based compact ultra-wideband (UWB) hybrid coupler is developed for Ku-band applications. The coupler is developed using the substrate-integrated gap waveguide (SIGW) technology. The coupler structure consists of two layers, the bottom layer represents the artificial magnetic surface of the periodic s...
The water demand is proportionally increasing with the world growing population, increasing urbanization, and changing living standards. Turkey is a country that suffers from water scarcity. Although Central Anatolia of Turkey has important basins such as Lake Tuz and Beysehir Lake, these basins suffer from drying up. Therefore, monitoring the sust...
—This paper presents the design and measurements of a dual-band Triple H-Defected Ground Structure (Triple H-DGS) antenna. DGS has proven to be successful in the design of multiband antennas; however because of the lack of a standard approach, the determination of the exact position of the Triple H-DGS requires rigorous and lengthy numerical comput...
Machine learning has been used in this work for the development of a Ku band Ridge Gap Waveguide (RGW) slot antenna loaded with an FSS superstrate for satellite internet applications. The structure operates from 13.25 to 14.75 GHz with a gain beyond 10 dB using FSS superstrate loading. The developed machine learning model aims to predict the optima...
This work is devoted to the development of a high gain frequency Selective Surface (FSS) reflector-backed monopole antenna using Machine Learning (ML) techniques for 5G applications. It analyzes and solves the complexity of the determination of the optimum position of the FSS reflector and the ground dimension of the monopole in this composite ante...
This study proposes an ultra-wideband Koch Snowflake fractal patch antenna with crescent star-shaped slot for Radio Frequency (RF) energy harvesting. The antenna, designed as the third iteration, covers the GSM1800 (1.8GHz) and Wi-Fi (2.4 GHz) frequency bands and operates in the 1.57 GHz-2.53GHz frequency range. It has an impedance of 50 Ω and is f...
This study proposes a new design of a double-layered metamaterial-based triple band perfect absorber aimed at harvesting microwave energies for 5G applications. The developed unit cell is formed by the combination of two letters-shape patches on a grounded dielectric substrate. The spacing between the two layers is varied between one and half wavel...
In this study, we consider chromospheric heating models for 55 Cancri in conjunction with observations. The theoretical models, previously discussed in Paper I, are self-consistent, nonlinear and time-dependent ab-initio computations encompassing the generation, propagation, and dissipation of waves. Our focus is the consideration of both acoustic...
In this study, we consider chromospheric heating models for 55 Cancri in conjunction with observations. The theoretical models, previously discussed in Paper I, are self-consistent, nonlinear and time-dependent ab-initio computations encompassing the generation, propagation, and dissipation of waves. Our focus is the consideration of both acoustic...
In this manuscript, H-slotted DGS-based antenna configuration for K/Ku applications is designed, fabricated, and measured using ROHDE & SCHWARZ ZVB20 network analyzer. Simulation studies are performed using Electromagnetic Simulation Software CST Studio Suite. Moreover, the development of the Artificial Neural Networks (ANN) model is implemented ba...
This paper proposes a novel design of compact and thin metamaterials (MMs) based wideband absorber aiming at specific microwave energy harvesting for 5G applications. The developed unit cell is obtained by combining two letters-like patches printed on a grounded dielectric substrate. The developed operating band is achieved based on the superpositi...
The proposed work conducts a new approach for modeling a dual band monopole antenna design using DGS assisted by ANN. In the aim of efficient dual band antenna design with gain and optimal impedance matching, the Artificial Neural Networks technique (ANN) is used for the development process. This work presents a modeling for H-slotted Defected Grou...
We present theoretical models of chromospheric heating for 55 Cancri, an orange dwarf of relatively low activity. Self-consistent, nonlinear and time-dependent ab-initio numerical computations are pursued encompassing the generation, propagation, and dissipation of waves. We consider longitudinal waves operating among arrays of flux tubes as well a...
We present theoretical models of chromospheric heating for 55 Cancri, an orange dwarf of relatively low activity. Self-consistent, nonlinear and time-dependent ab-initio numerical computations are pursued encompassing the generation, propagation, and dissipation of waves. We consider longitudinal waves operating among arrays of flux tubes as well a...
This paper analyzes and solves the complexity to determine the optimum positions of the Fishnet & Complementary Circular Ring Resonator (CCRR) based Defected Ground Structures (DGS) for Substrate Integrated Waveguide (SIW) based antennas. A new state of-art technique based on Artificial Neural Network (ANN)-Machine Learning (ML) is proposed for ove...
Terrestrial water storage (TWS) data derived from past Gravity Recovery and Climate Experiment (GRACE; April 2002–June 2017) and current GRACE-Follow On (GRACE-FO; June 2018–present) missions provide insights into mass transport within, and between, different Earth’s systems. In 2017 Earth Science Decadal Survey, a future gravity mission (GRACE-II;...
A dual band Substrate Integrated Waveguide; SIW microstrip patch antenna based on periodic H-Defected Ground Structure; H-DGS is designed for Ku band applications. SIW techniques provide low cost, small size and convenient integration with planer circuit. The proposed antenna structure is designed on a Roger 5058 substrate with a thickness of 1.6 m...
The 6G race has already begun, and many countries
and giant corporations started directing significant efforts and
funds towards the development of the future technology. The 6G
standard is expected to migrate to higher bands of frequencies
to support wider bandwidth. Through this wide bandwidth, it
will be feasible to serve the expected massive nu...
The near-to-launch 5G standard for wireless communications did not seal the ultimate use the mm-wave bands. As a result, the future 6G standard is expected to proceed in
more efficient utilization of these bands. One of the most critical elements in the RF link is the amplifier, especially when the attenuation of the channel is relatively high whic...
Power dividers are critical components for mm-wave
applications. They are used in antenna feeding structures to
provide the suitable excitation in the antenna array systems and deployed in microwave smart beam switching subsystems. In this article a dual gap wideband in-phase power divider is presented. The bandwidth starts at 19 and ends at 40 GHz...
The fifth generation (5G) is the next wireless mobile communication technology that targets to provide huge capacity, low latency and high data speeds. Like any new wireless
technology, 5G requires the development of exciting techniques, where access to high frequency spectrum can achieve the desired characteristics. In addition, new systems must b...
The aim of the current study is the computation of the magnetic flux
tube wave energies and fluxes generated in the convection zone of Procyon A.
This is a subgiant of spectral type F5 IV-V showing chromospheric and coronal
activities. The mechanisms responsible for the generation of different wave
modes include the interaction of the thin and vert...
In the current work, a new Wideband Substrate
Integrated Waveguide Bandpass Filter (SIW-BPF) is presented.
The target is to allow vertical roaming between the X and Ku band
applications. As a first step, we performed a parametric study of
different etched slot geometries namely, H-Slotted, T-Slotted, and
U-Slotted DGS in order to examine the effect...
This paper presents the design and
fabrication of a directional antenna for the Traffic
alert and Collision Avoidance avionic System
(TCASII). A patch antenna in a circular shape made
from copper. Roger 5880 with h= 3.18 mm;εr =2.2,
and loss tangent of 0.0009 is taken as a substrate
material. It is fed using a microstrip line of 50 ohm.
It operates...
This paper presents the effect of Metamaterials (MTMs) unit cells on the performance of LTE wide band antenna. It is a conventional rectangular patch antenna with dimension of 10 mm x 6 mm. It is implemented on FR-4 lossy substrate material with relative permittivity of εr = 4.4, thickness of 1.6 mm and loss tangent of 0.025. It is feed through a m...
This paper presents the effect of Metamaterials (MTMs) unit cells on the performance of LTE wide band antenna. It is a conventional rectangular patch antenna with dimension of 10 mm x 6 mm. It is implemented on FR-4 lossy substrate material with relative permittivity of εr = 4.4, thickness of 1.6 mm and loss tangent of 0.025. It is feed through a m...
On the way to design Substrate Integrated Waveguide Bandpass Filter (SIW-BPF) for wideband applications a parametric study of the slot geometry etched on a SIW structure is the preliminary step to design such filter.
Three different structures, namely, H-Slotted, T-Slotted, and U-Slotted SIW is investigated in order to examine the effect of alterin...
This work discusses theoretical models of chromospheric
heating for epsilon Eridani by shock waves. Self consistent,
nonlinear and time-dependent ab-initio numerical
computations for the excitation of the atmosphere (i.e.,
arrays of flux tubes) are pursued based on waves generated
in stellar convective zones. Based on previous studies the
magnetic...
In the current study we present ab initio numerical computations of the generation and propagation of longitudinal waves in magnetic flux tubes embedded in the atmospheres of late-type stars. The interaction between convective turbulence and the magnetic structure is computed and the obtained longitudinal wave energy flux is used in a self-consiste...
Communication network plays a significant task in distribution system of
smart grid when it comes to sending and receiving the bi-directional flows of
communication data, information and important control messages between the
sending (Intelligent Electrical Device) IED and receiving IED of the components
of smart grid in a coupling network (Power a...
The predicition of structural reactions to big earthquakes is vital in
giving warnings for potential damages early enough to minimize
losses of life and properties. In the current study we describe
buildings by fixed construction and environmental related parameters.
Our models are based on real data of damaged buildings collected
after the oc...
From our Secret Lives of Cepheids program, the prototype Classical Cepheid, $\delta$ Cep, is found to be an X-ray source with periodic pulsation-modulated X-ray variations. This finding complements our earlier reported phase-dependent FUV--UV emissions of the star that increase $\sim$10--20 times with highest fluxes at $\sim0.90-0.95\phi$, just pri...
From our Secret Lives of Cepheids program, the prototype Classical Cepheid, $\delta$ Cep, is found to be an X-ray source with periodic pulsation-modulated X-ray variations. This finding complements our earlier reported phase-dependent FUV--UV emissions of the star that increase $\sim$10--20 times with highest fluxes at $\sim0.90-0.95\phi$, just pri...
Self-consistent, nonlinear and time-dependent numerical computations of the excitation of chromo-
spheric oscillations in a thin and non-isothermal magnetic flux tube embedded in magnetic-free atmospheres of late-type stars are performed. Longitudinal tube waves are considered and the wave energy spectra and fuxes generated in convective zones of t...
The current work is an attempt to predict building reactions to big earthquakes using real data collected from surveys carried out after the occurrence of earthquakes. With the development of building damage functions for big earthquakes in Turkey one can predict the damage levels as a function of earthquakes’ intensity and the building parameters....
Computations of chromospheric models and the resulting spectral line emission fluxes are presented for late-type stars exhibiting
very low level of chromospheric activity, referred to as a basal flux stars or low activity stars. The computations are self-consistent,
and consider the entire acoustic wave energy spectra generated in the stellar conve...
In the current study we present radiation correction factors to compute the radiative
losses by Mg~II and Ca~II ions during the process of constructing theoretical models
for the chromospheres in late-type stars (spectral type in the range F5V - K8V).
We combine the two-level atom approach with the multi-level atom method to accurately
compute the...
BODY: We are analyzing ERS-1 and ERS-2 and ENVISAT data to measure the spatial and temporal variations in three tectonically active areas near Izmit, Duzce and Van provinces in Turkey. We are using ERS-1 and ERS-2 data sets, which provide a longer time period of coverage (1992 to 2001). In addition, we will extend this forward to the present with E...
In the present work we expand the study of time-dependent ionization
previously identified to be of pivotal importance for acoustic waves in solar
magnetic flux tube simulations. We focus on longitudinal tube waves (LTW) known
to be an important heating agent of solar magnetic regions. Our models also
consider new results of wave energy generation...
The main aim of this paper is to perform first self-consistent numerical computation of the response of stellar atmospheres to the propagation of acoustic waves specified by realistic acoustic wave energy spectra. In the numerical approach, stellar atmospheres are stratified, non-isothermal and plane-parallel, and only their magnetic-free regions a...
a b s t r a c t The formation of shocks and shock heating by radiatively damped longitudinal waves in solar magnetic flux tubes of different filling factors is studied. We consider three flux tubes of filling factors: 1%, 20%, and exponentially spreading which represent normal, enhanced network regions and the interior of supergranulation cells res...
This paper presents a high level design for a scalable and extendable real-time hazard reporting and loss estimation system (RT-HRLE) which helps evaluating the initial estimation of economic losses in case of natural or man-made disasters. The system allows real-time monitoring, tracking of missed people inside buildings and reports partial or tot...
Context. Continued investigation of the linkage between magneto-acoustic energy generation in stellar convective zones and the energy dissipation and radiative emission in outer stellar atmospheres in stars of different activity levels. Aims. We compute the wave energy fluxes carried by longitudinal tube waves along vertically oriented thin magneti...
A modified theory of turbulence generation is combined with the magnetohydrodynamic equations to numerically compute the wave
energies generated at the base of magnetic flux tubes for stars with effective temperatures ranging from Teff= 3000 to 7000 K, gravity log g= 4.44 and with different metal abundances: solar, 0.1, 0.01 and 0.001 of solar meta...
a b s t r a c t Equivalent widths for four FeH bands (0–0), (1–0), (2–0), and (2–1) versus rotational quantum number J have been used to determine the rotational temperature of the molecule. The average value obtained from the first three bands is T rot ¼ 2900 K AE 300 K. This result agrees well with the temperatures derived for other molecules in...
The heating mechanisms of the solar chromosphere are still under
discussion. Helpful for this topic is to look for basal flux stars that
are similar to the Sun.
The minimum observed CaII H+K & MgII h+k line fluxes from stellar
Chromospheres as function of effective temperature Teff are called basal
flux lines. It is widely thought that these fluxe...
The heating mechanisms of the solar chromosphere are still under discussion. Helpful for this topic is to look for basal flux
stars that are similar to the Sun.
The minimum observed CaII H+K & MgII h+k line fluxes from stellar Chromospheres as function of effective
temperature Teff are called basal flux lines. It is widely thought that these fluxes...
A fast and reasonably accurate method for calculating the total radiative losses by Ca ii and Mg ii ions for time-dependent chromospheric wave calculations has been developed. The method is based on a two-level atom procedure with pseudo–partial frequency redistribution (pseudo-PRD). The speed of the method is due to scaling of the total losses fro...
In the first paper of this series we developed a method to construct theoretical, time-dependent and two-component chromosphere models for late-type main sequence stars. The models consist of non-magnetic regions heated by acoustic waves and magnetic flux tube regions heated by magnetic tube waves. By specifying the magnetic filling factor, theoret...
Theoretical chromospheric models described in the two previous papers of this series are used to study the relationship between the chromospheric emission and the filling factor. This theoretically determined relationship shows that the chromospheric emission flux in Ca II (H+K) is approximately proportional to the square root of the magnetic filli...