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

Research Output
Now showing 1 - 2 of 2
  • Publication
    A flexible wearable linear-to-circular polarizer for GNSS application
    (Institute of Electrical and Electronics Engineers (IEEE), 2020)
    Hidayath Mirza
    ;
    Ping Jack Soh
    ;
    Rais Ahmad Sheikh
    ;
    Azremi Abdullah Al-Hadi
    ;
    Toufiq M Hossain
    ;
    Sen Yan
    This paper presents a single-layered fabric-based flexible linear-to-circular polarizer for GNSS application operating at 1.575 GHz. The structure presented here is based on a square aperture with an E-shaped patch structure on the reverse side. The size of the structure is 0. 21λ0 ×0. 26λ0 × 0. 01λ0 The complete structure is flexible, and the frequency of operation is centered at 1.575 GHz, with a minimum value of the axial ratio achieved is 0.06 dB. The 3 dB axial ratio fractional bandwidth is 3.81% (1.54-1.60 GHz) and the conversion efficiency fractional bandwidth covering 90% is 5.09% (1.53 to 1.61 GHz).
  • Publication
    A triband wearable antenna for location tracking using cospas-sarsat and GNSS
    (IEEE, 2025)
    Rais Ahmad Sheikh
    ;
    Azremi Abdullah Al-Hadi
    ;
    Roy B. V. B. Simorangkir
    ;
    Thennarasan Sabapathy
    ;
    Rizwan Khan
    ;
    Prayoot Akkaraekthalin
    ;
    Surentiran Padmanathan
    ;
    Toufiq Md Hossain
    ;
    Che Muhammad Nor Che Isa
    ;
    Ping Jack Soh
    This paper presents the design of a tri-band antenna operating in the Cospas-Sarsat (C-S) and GPS/GNSS bands applicable for the Internet of Things (IoT). Implemented with flexible and robust materials, the antenna operates in three distinct frequencies: 406 MHz for C-S applications and 1227 MHz (L2) and 1575 MHz (L1) for GPS/GNSS applications. The measured 10-dB impedance bandwidth is from 1.517-1.587 MHz (in L1 band) and from 1.192-1.232 MHz (in L2 band). In C-S band, the measured 6-dB bandwidth is from 393 to 406.5 MHz. The 3 dB axial ratio (AR) bandwidth in the L1 and L2 bands are 17 MHz (1.08%) and 18 MHz (1.47%), respectively. The antenna demonstrates a measured gain of 1.61 dB at 406 MHz, exceeding the simulated gain of 0.573 dB, and features a beamwidth of 140°. The measured gains for the L2 and L1 bands closely align with the simulations, although a slight reduction in gain is observed for the L2 band. In the H-plane, zenith-directed main lobes produce measured gains of 1.61 dB for 406 MHz, 2.71 dB for L2, and 3.51 dB for L1. On the other hand, the measured efficiency for the antenna is 36.32% (in the C-S band), 54% (in L1 band) and 60.12% (in L2 band). Both measured and simulated results consistently showed good agreements in terms of gain, polarization, and efficiency. Moreover, the antenna design incorporates effective shielding against electromagnetic radiation, conforming to specific absorption rate (SAR) values of 0.046, 0.077, and 0.035 W/Kg in C-S, L1 and L2 bands respectively. Antenna integration into the life vest foam prior to placement on the human chest significantly influenced axial ratio variations. In the L1 band, the AR increased from 0.43 dB to 3.34 dB, while in the L2 band, it rose from 0.56 dB to 8.66 dB. This indicates a more pronounced effect on polarization characteristics at the lower frequency. Overall, the proposed tri-band antenna presents promising capabilities for location tracking applications, with potential for integration into wearable devices for enhanced safety and tracking functionalities.