Azremi Abdullah Al-Hadi
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Preferred name
Azremi Abdullah Al-Hadi
Official Name
Azremi, Abdullah Al-Hadi
Alternative Name
Abdullah Al-Hadi, Azremi
Al-Hadi, Azremi A.
Al-Hadi, A. A.
Azremi, A. A. H.
Main Affiliation
Scopus Author ID
57194469675
Researcher ID
A-6983-2015

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Now showing 1 - 7 of 7
  • Publication
    An ultrawideband full flexible 4 elements DGS based MIMO antenna for Sub-6 GHz wearable applications
    (IEEE, 2024-03)
    Bikash Chandra Sahoo
    ;
    Azremi Abdullah Al-Hadi
    ;
    Saidatul Norlyana Azemi
    ;
    Surentiran Padmanathan
    ;
    Sadia Afroz
    ;
    Wee Fwen Hoon
    ;
    Soh Ping Jack
    ;
    Che Muhammad Nor Che Isa
    ;
    Soumya Ranjan Mishra
    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 coupling between the radiating elements. The antenna is evaluated in terms of reflection coefficient, gain, efficiency, and radiation pattern. The proposed MIMO antenna attained a maximum simulated gain of 4.3 dBi, and an efficiency of 96 % in the resonating band.
  • Publication
    A 3.5 GHz wearable antipodal vivaldi antenna for 5G applications
    (IEEE, 2024-01)
    Sadia Afroz
    ;
    Azremi Abdullah Al-Hadi
    ;
    Surentiran Padmanathan
    ;
    Saidatul Norlyana Azemi
    ;
    Wee Fwen Hoon
    ;
    Bikash Chandra Sahoo
    ;
    Yen San Loh
    ;
    Che Muhammad Nor Che Isa
    ;
    Lun Hao Tung
    ;
    Lai Ming Lim
    ;
    Zambri Samsudin
    ;
    Idris Mansor
    ;
    Soh Ping Jack
    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.
      10  2
  • Publication
    A study and investigation of small antenna efficiency measurement using reverberation chamber
    ( 2006)
    Azremi Abdullah Al-Hadi
    ;
    Soh Ping Jack
    ;
    Anuar Mat Safar
    Numbers of small antennas were designed and various kind of antennas were tested for measurement. Amplitude fluctuations in signals received over mobile radio channels are typically modeled by Rayleigh distribution. The field statistics in the volume of the enclosure are shown to correspond to the Rayleigh statistics found in properly functioning reverbration chambers when a sufficiently large number of modes are excited. The purpose of this paper is to show that the antenna efficiency can be measured accurately in much faster, easier and cost effectively reverberation chamber using three different antennas (two monopole antennas with attenuator and surface mount resistor, and modified folded monopole patch antenna). It also gives an investigation of the statistical characteristics in Rayleigh communications channels by using reverberation chamber. Scattering parameters taken from the measurement of the antenna radiation efficiency using reverberation chamber is implemented into Rayleigh Probability Density Function (PDF) model and it really shows that they are in good agreement with those of theoritically predicted Rayleigh model.
      17  23
  • Publication
    Horn Antenna Gain Enhancement using 3-D Printed Dielectric Lens for Dielectric Properties Measurement
    ( 2023)
    Renukka Sivakumar
    ;
    Saidatul Norlyana Azemi
    ;
    Azremi Abdullah Al-Hadi
    ;
    Zahari Awang Ahmad
    ;
    Kok Yeow You
    ;
    Lee Yeng Seng
    ;
    Soh Ping Jack
    A 3-D printed dielectric lens for gain enhancement of horn antenna from 18 GHz to 40 GHz is presented in this paper. Fused deposition modelling (FDM) is used to fabricate the Acrylonitrile butadiene styrene (ABS) lensas it is one of the well-known 3-D printing techniques. The results with and without dielectric lens are analyzed and compared from the simulation. From simulation results with thedielectric lens, a maximum gain of 26.7 dBi was achieved. The dielectric lens of 21.72 mm thickness was able to provide a gain enhancement up to 26.7 dBi when compared to the simulation result without the dielectric lens. The proposed dielectric lens can improve the gain of the horn antenna as good agreement between literature, simulation and measurement was achieved.
      7  3
  • Publication
    Compact full flexible vivaldi antenna for 3.5 GHz wearable applications
    (IEEE, 2023)
    Bikash Chandra Sahoo
    ;
    Azremi Abdullah Al-Hadi
    ;
    Saidatul Norlyana Azemi
    ;
    Wee Fwen Hoon
    ;
    Surentiran Padmanathan
    ;
    Sadia Afroz
    ;
    Che Muhammad Nor Che Isa
    ;
    Yen San Loh
    ;
    Muhammad Syahir Mahyuddin
    ;
    Lai Ming Lim
    ;
    Zambri Samsudin
    ;
    Idris Mansor
    ;
    Soh Ping Jack
    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 (εr) 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 (length × width × height). The antenna is evaluated in terms of reflection coefficient, gain, efficiency, radiation pattern, and surface current density. This antenna attained a maximum simulated gain of 4.7 dBi, and an efficiency of 98 % in the resonating band.
      7  1
  • Publication
    A Hybrid Mutual Coupling Reduction Technique in a Dual-Band MIMO Textile Antenna for WBAN and 5G Applications
    ( 2021-01-01)
    Hamza A. Mashagba
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Ismahayati Adam
    ;
    Jamaluddin M.H.
    ;
    Mohd Najib Mohd Yasin
    ;
    Muzammil Jusoh
    ;
    Thennarasan Sabapathy
    ;
    Abdulmalek M.
    ;
    Azremi Abdullah Al-Hadi
    ;
    Arif Mawardi Ismail
    ;
    Soh Ping Jack
    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 dimensioned at 47.2 × 31 mm2. This hybrid technique results in a simple structure, while enabling significant reduction of mutual coupling (MC) between the closely spaced patches (up to 0.1 λ). This technique combines a line patch and a patch rotation technique, explained as follows. First, a line patch is introduced at an optimized distance to enable operation with a broad impedance bandwidth at both target frequencies. One of the patches is then rotated by 90° at an optimized distance, resulting in a significant MC suppression while maintaining the dual and broad impedance bandwidth. The proposed MIMO antenna is further evaluated under several bending configurations to assess its robustness. A satisfactory agreement between simulated and measured results is observed in both planar and bending conditions. Results show that the MIMO antenna achieves an impedance bandwidth of 4.3 % and 6.79 % in the 2.45 GHz and 3.5 GHz band, respectively. Moreover, very low MC (S21 <-30 dB) is achieved, with a low (< 0.002) envelop correlation coefficient, and about 10 dB of diversity gain at both desired frequencies using this technique. Even when bent at an angle of 50° at the x-and y-axes, the antenna bent maintained a realized gain of 1.878 dBi and 4.027 dBi in the lower and upper band, respectively. A robust performance is offered by the antenna against the lossy effects of the human body with good agreements between simulated and measured results.
      2  29
  • Publication
    Narrowband to Narrowband Frequency Tunable Slotted Dipole Antenna
    ( 2021-03-01)
    Rabbil Izziety Mohd Rodi
    ;
    Mohamed Nasrun Osman
    ;
    Mohammad Kamal Abd Rahim
    ;
    Muzammil Jusoh
    ;
    Thennarasan Sabapathy
    ;
    Azremi Abdullah Al-Hadi
    ;
    Soh Ping Jack
    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 longest dipole length produced 1.8 GHz, the second-longest dipole length produced 2.4 GHz, the third-longest dipole length produced 2.6 GHz, while the smallest dipole length produced 3.5 GHz. To maintain the stability of the RF current in the system, sixteen capacitors were used. As well eight inductors were used to isolate the RF current and power supply. The PIN diode was used as a switch to allow the induced current to stop and pass into the slot which means that it can be used to select the desired frequency. Depending on switching configuration, the operating frequency is tuned. Good matching is achieved for all configurations. The simulated result of gain for the four operating is higher than 2 dB while the omnidirectional radiation pattern has been obtained thus makes the proposed antenna suitable for wireless application.
      6  1