
Azremi Abdullah Al-HadiUniversity of Malaysia, Perlis | unimap · School of Computer and Communication Engineering
Azremi Abdullah Al-Hadi
D.Sc (Technology) in Radio Engineering
About
218
Publications
91,863
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Introduction
Azremi Abdullah Al-Hadi was born on August 26 in Michigan, United States of America. He received the Master of Science degree in communication engineering from Birmingham University, United Kingdom in 2004 and the Doctor of Science (Technology) degree from Aalto University, Finland in 2013. His current research interests include design and performance evaluation of multi-element antennas, mobile terminal antennas and their user interactions, and wireless propagation.
Additional affiliations
September 2016 - present
June 2010 - August 2016
August 2003 - August 2004
Education
November 2008 - November 2013
August 2003 - August 2004
July 1999 - April 2002
Publications
Publications (218)
This paper emphasizes the performance analysis
of a flexible wearable antenna designed for 5G applications near
a human body model. The antenna, measuring 55×46×0.4 mm³,
features a slotted circular ring patch as the radiating element on
a polyester wearable substrate and a partial ground plane on the
back. It provides a bandwidth of 300 MHz between...
In this article, a compact wearable quad element
MIMO antenna is presented operating at 4.5 GHz for 5G n77,
n78, and n79 bands with the use of polyester substrate with a
size of 80 × 82 × 0.4 mm3. Here T-shaped defected ground
structure (DGS) technique has been utilized to improve the
impedance bandwidth along with the reduction of the mutual
coupl...
In this paper, a compact wearable Vivaldi
antenna resonating at 3.5 GHz is proposed for 5G n77, and n78
bands. It is designed upon a flexible polyester substrate having
dielectric constant (ɛr) of 1.34 and loss tangent (tan δ) of 0.005.
The antenna parameters were optimized via parametric
analyses using CST software with a size of 45 × 45 × 0.4 mm3...
This paper represents a wideband wearable
antenna for 5G applications. In this proposed design, an
antipodal vivaldi antenna structure is implemented on a
polyimide and polyester combined substrate. The 120 × 95 × 0.82
mm3 sized antenna acquired a wide bandwidth of 910 MHz with
a realized gain of 5.42 dBi and efficiency of 96 percent.
The present invention discloses an antenna assembly (100) for reducing mutual coupling and radiation loss of a device which comprises a substrate (110), dual antenna elements (120) including a first antenna element (121) and a second antenna element (122) and feeding mechanisms (130). Further, two ground planes (114) are sandwiching on top and bott...
n this paper, a dual band wearable antenna for5G applications that resonates at 3.63 GHz and 4.95 GHzcovering sub-6 GHz 5G-NR bands such as n48, n77, n78, andn79 is presented. The antenna consists of slotted circular ringpatch as radiating element, polyester as wearable substrate, anda partial ground plane on the bottom. The designed antenna issize...
An empirical method for simplified dimension estimation of patch antennas is proposed in this work based on characteristic mode analysis (CMA). This method involves generating formulae to calculate substrate-independent antenna patch widths produced from the antenna’s characteristic angle. This enables the definition of a relationship between the c...
Wireless communications infrastructure is an important lifeline during natural disasters such as floods. The scope of the project is to design a drone-based free space optical spatial mode diversity system.
A novel wideband self-decoupled loop-coupled antenna element is proposed for the fifth-generation (5G) multiple-input multiple-output (MIMO) smartphones. The proposed loop-coupled antenna element generates two resonance modes of 0.75 and 1 λ. With the help of these two resonance modes, a wide bandwidth is achieved. The self-decoupled performance is...
This paper presents a low-profile textile scorpion patch antenna for wearable applications. The modal behaviors of the proposed antenna are investigated by using the theory of characteristic modes analysis (CMA). Four characteristic modes with the same resonant frequencies and orthogonal current distributions are chosen for operation. The proposed...
In this paper, a method of designing antennas by avoiding crossing between the modes is presented. This is aimed at enhancing antenna bandwidth using ground fragmentation techniques based on the characteristic modes analysis (CMA) approach. A compact and flexible Saxophone antenna and a conventional rectangular microstrip antenna both dimensioned a...
The paper presents the design and analysis of a corona-shaped fractal antenna with a defected ground structure (DGS) for wireless applications. The fractal concept with an inverse patch medium DGS (IPM-DGS) technique is proposed and applied to achieve multi-band frequencies with a high efficiency. The same structure on the top face of the antenna i...
A rectangular microstrip patch array antenna (RMPAA) for 6GHz WiFi communication has been presented in this paper. The RMPAA designed on Rogers RT 5880-operates at 6.41 GHz covering 5.5356 GHz to 7.0449GHz. The antenna possesses a wide bandwidth of 1.5093 GHz with a good gain (Max. 3.52 dB) and directivity (Max. 4.2 dBi). The existence of a rectang...
In this paper, the design of a multiband multiple-input multiple-output (MIMO) antenna with frequency and radiation pattern reconfiguration capability in the 5G sub-6 GHz band is presented. Frequency and radiation pattern reconfiguration are enabled on the antenna consisting of two planar inverted-F antenna (PIFA) elements using PIN diodes and DC b...
This work studies the correlation between 14-elements of a sub-6 GHz MIMO antenna for mobile terminal, operating in the 3.10 to 3.85 GHz frequency band. Envelope correlation coefficient (ECC) was used to assess the relationship between MIMO antenna elements. A total of 91 ECC values were considered at every frequency point for the 14-element antenn...
This paper studies the performance of a 14-element dual-band 5G MIMO antenna with body effect and an antenna selection. The antenna operates in the lower frequency band from 3.10 to 3.85 GHz for 5G bands of LTE 42 and 43, whereas the upper band is from 5.60 to 7.20 GHz for the newly assigned 6 GHz WiFi band. The antenna performance was evaluated in...
In this paper, a dual band radiation pattern reconfigurable antenna for 5G mobile terminals is presented. Two identical PIFA elements are connected to a PIN diode and feeding port to enable reconfiguration. Copper strips are used as RF switches in this antenna design to represent the actual PIN diodes. The switching of the two PIFA elements in sequ...
This paper presents a hybrid mutual coupling reduction technique applied onto a dual-band textile MIMO antenna for wireless body area network and 5G applications. The MIMO antenna consists of two hexagonal patch antennas, each integrated with a split-ring (SR) and a bar slot to operate in dual-band mode at 2.45 GHz and 3.5 GHz. Each patch is dimens...
Characteristic modes (CM) can be used to solve many radiation and scattering problems involving fully conducting structures. The basic concept is to use eigenvalues and eigenvectors of the characteristic mode equations of a certain topology, and to use these eigenmode currents to control the radiating structure’s behavior. This is accomplished by u...
In this paper, a Dual Monopole Frequency Reconfigurable Antenna (DMFRA) for two port Multiple Input Multiple Output (MIMO) Fifth Generation (5G) sub-6 GHz mobile terminal is presented. A combination of dual monopole strips is implemented at a port, respectively to achieve tunable and fixed resonant frequencies. Varactor diode is utilized in this de...
Various decoupling methods were proposed and investigated for multiple-input multiple-output (MIMO) Base Station (BS) systems. These methods can effectively decouple the dual-polarized co-polar signal but fail to decouple the cross-polarized signal, similarly limiting the BS's overall decoupling performance. In this paper, different antenna arrays...
A compact crown-shaped planar antenna integrated with a 3 × 3 artificial magnetic conductor (AMC) ground is presented for wearable internet of things communications. Simulations were performed using the commercial software FEKO based on two approaches: characteristic mode analysis and the method of moments. This paper aims to optimize the operation...
In this work, the design procedure of a new decoupling network for different antennas is presented for mobile terminals operating in the Sub-1 GHz band (from 0.698 to 0.96 GHz). To evaluate its applicability for different resonant and non-resonant antenna types, two antenna elements have been chosen to be decoupled using the proposed decoupling net...
This work presents the design and optimization of an antenna with defected ground structure (DGS) using characteristic mode analysis (CMA) to enhance bandwidth. This DGS is integrated with a rectangular patch with circular meandered rings (RPCMR) in a wearable format fully using textiles for wireless body area network (WBAN) application. For this i...
This paper presents an active mode subtraction method based on the characteristic mode analysis to estimate the forward directivity based on the difference in modal significance curves. This made the optimization of the antenna gain in the design process to be more efficient. To the best of the authors’ knowledge, such method is innovative and prop...
In this paper, the slotted dipole antenna structure is proposed to have four narrowband frequencies with ability to be reconfigured. Narrowband reconfiguration can be achieved by controlling the length of slotted dipole by using switches. The narrowband frequency is to be at 1.8 GHz (GSM), 2.4 GHz (WLAN), 2.6 GHz (4G), and 3.5 GHz (5G) respectively...
The design of a compact, wideband flexible monopole antenna printed on a flexible Kapton polyimide substrate is presented. The proposed antenna consists of two rhombic elements embedded within a square plane as the radiating element. The wide bandwidth is aimed at alleviating potential performance degradations due to its application in an on‐body e...
This paper investigates the effect of index finger position and distance on the radiated power of 4-element MIMO antenna, operating at 28 GHz. The antenna elements (AEs) are located at the top corner of the user terminal and separated at a distance of half a wavelength. Four different finger placements were investigated, one placement over each AE...
A wearable textile antenna with dual-band and dual-sense characteristics is presented in this work. It operates at the 2.45 GHz band for WBAN and WLAN applications, and at the 1.575 GHz band for Global Positioning System (GPS) applications. An antenna backing based on an artificial magnetic conductor (AMC) plane operating at 2.45 GHz band is introd...
This paper presents results of maximal ratio combining (MRC) technique of dual-band 4-element MIMO antenna with user's hand in data mode and different placements of antenna elements (AEs) on the chassis. The different placements start from worst case to optimal which is selected to avoid thick tissues of the hand. The dual 5G frequency bands are fr...
A dual band slot dipole antenna made from textile is proposed for Wireless Body Area Network and Wireless Local Area Network applications. The proposed antenna is integrated with an artificial magnetic conductor plane to mitigate backward radiation and reduce Specific Absorption Rate when operated on body. The artificial magnetic conductor plane is...
This paper investigates the performance variation when a different number of antenna elements (AEs) is integrated onto a single MIMO mobile terminal, both in free space and when held in a user hand in data mode. Starting with a minimum of two AEs, this investigation assessed the performance of the MIMO terminal with every additional two AEs (up to...
In this work, a mutual coupling reduction technique for multiple antennas designed on small chassis is investigated. This technique is based on introducing a meander-shaped defected ground structure (DGS) unit cell located on the top edge in between two planar inverted-F antennas (PIFAs). It functions as a filter to improve the isolation between an...
Two new flexible, single-sided linear-to-circular polarizers based on the square loop unit cells have been proposed in this work. The first uses a flexible Polydimethylsiloxane (PDMS) substrate, whereas the second polarizer is implemented on a felt textile substrate. Both polarizers uses the same ShieldIt textile to form their conducting elements....
A concept of using dual-polarized, three dimensional antenna elements with minimized current distribution on ground plane to reduce the effects of user’s hand on a mobile terminal operating in LTE-U 5G band is proposed. This method which also minimizes mutual coupling (MC) is studied using a structure consisting of two non-identical antenna element...
This paper evaluates the performance of different configurations of MIMO antenna operating in the 5G band with the effect of user's hand in data mode and suggests an optimized configuration to mitigate hand effects. A dual-band four-element MIMO antenna is used. All antenna elements (AEs) are identical planar inverted-F antenna (PIFAs) with a lower...
In this paper, the influence of user’s hand on mobile terminal antenna when it placed approximately on top of Multiple Input Multiple Output radiating element antennas (PIFAs) is studied extensively. The antenna is designed to operate at 5 GHz with 1.5 GHz of -6 dB bandwidth. The effect of user’s hand with different finger positions are studied at...
A printed Yagi-Uda antenna with two closely-spaced driven dipole elements and truncated ground plane is presented for dual-band operation. It is designed on a low-cost FR4 substrate with a dielectric constant 4.6, loss tangent of 0.02, and thickness of 1.6 mm. The dipole, operating in the lower band (centered at 1.8 GHz), is elliptical-bow-tie in s...
This paper is introduced a passive sensor to detect the performance of the structure using three-dimensional (3D) Frequency Selective Surfaces (FSS). The proposed 3D Circular FSS results are proved behave as passive sensor with changing of sensitivity incident angles to be apply in Structural Health Monitoring (SHM) system. Moreover, this 3D Circul...
The use of energy saving glass has become very popular in the modern day building design. This energy saving property is achieved by applying a very thin tin oxide (SnO2) coating on one side of the glass. This coating can provide good thermal insulation to the buildings by blocking infrared rays while being transparent to visible part of the spectr...
The design of directive antenna using Frequency Selective Surface (FSS) superstrate is proposed in this project. The suitable design FSS as superstrate layer is very important to enhance the high directivity and narrow bandwidth on the antenna. By using the FSS layer to design the superstrate layer, there are able to determine the reflection coeffi...
Structural health monitoring (SHM) technologies have attained attention to monitor civil structures. SHM sensor systems have been used in various civil structures such as bridges, buildings, tunnels and so on. However the previous sensor for SHM is wired and encounter with problem to cover large areas. Therefore, wireless sensor was introduced for...
The capability of the flexible substrate of the frequency selective surface (FSS) to filter out particular frequency is discussed in this paper. A new type of FSS are applied using flexible thin plastic substrate to enhance the performance of the conventional FSS that lacks of flexibility and cannot be used in bending surface. A simulation based in...
This paper studies the effects of incident wave angular power spectrum (APS) distribution and user hand effect on the envelope correlation coefficient (ECC) of a two-port MIMO antenna operating in the sub 6 GHz LTE-U frequency band. APS of uniform and Gaussian distributions are used with different Gaussian angular spread (AS) values, i.e., 10 • , 3...
A wideband microstrip‐based wearable antenna with a fractional bandwidth of 51% is designed using textile materials for wearable applications. The antenna operates between 2 and 3 GHz with low back‐radiation to ensure minimum coupling to the body and reduced electromagnetic power absorption in the human tissue. The behavior microstrip antenna topol...
In this paper, two multiple input multiple output (MIMO) antennas for Wi-Fi/WLAN mobile applications are proposed. The designed two-port MIMO antennas are made up of planar inverted-F antennas (PIFAs). The antenna elements for both designs are symmetrical and placed on the short-edged corners of the substrate used, FR4. The performance of both ante...
This paper presents the performance evaluation of 2-port MIMO antenna for LTE-U sub 6 GHz band. The evaluation focuses on the effect of user’s hand in a uniform environment and the analysis were carried out on simulation and measurement data of antenna ports. Results show that the highest performance of the design is on the frequency range from 4.5...
In this paper, two multiple input multiple output (MIMO) antennas for Wi-Fi/WLAN mobile applications are proposed. The designed two-port MIMO antennas are made up of planar inverted-F antennas (PIFAs). The antenna elements for both designs are symmetrical and placed on the short-edged corners of the substrate used, FR4. The performance of both ante...
This paper presents a single layered textile-based flexible linear-to-circular polarizing surface. The proposed structure is designed based on a rectangular ring structure for CubeSat application in the S-band. Each unit cell is sized at 0.35λ×0.33λ×0.2λ for operation centered at 2.2 GHz. This unit cell is then multiplied into a 9x10 array to form...
This study is focused on highly coupled multiple antennas with defected ground slot techniques. Two Printed Inverted-F Antenna (PIFA) are positioned at the top edge of chassis symmetrically. Both antennas are operating at low-band Long-Term Evolution (LTE) with center frequency, 829MHz. Rectangular defected ground slot is implemented to reduce the...
This study is focused on highly coupled multiple antennas with defected ground slot techniques. Two Printed Inverted-F Antenna (PIFA) are positioned at the top edge of chassis symmetrically. Both antennas are operating at low-band Long-Term Evolution (LTE) with center frequency, 829MHz. Rectangular defected ground slot is implemented to reduce the...
A circuit model for a flexible linear-to-circular polarizer is
proposed. This linear-to-circular polarizer is designed
based on the concept of Frequency Selective Surface (FSS)
unit cells on one side and a rectangular-shaped conductive
strip (CS) on its reverse side. The overall polarizer is
implemented on a felt substrate, whereas ShieldIt Super
c...
In this paper, flexible, deployable linear to circular polarizers designed on Polydimethylsiloxane (PDMS) are proposed for the first time to the best of our knowledge. ShieldIt textile is used as the conducting elements of two types of unit elements: a loaded and an unloaded circular element on rear side of the substrate, and a generic rectangular...