Ismahayati Adam
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Preferred name
Ismahayati Adam
Official Name
Adam, Ismahayati
Alternative Name
Adam, I.
Ismahayati, A.
Adam, Ismahayati
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Scopus Author ID
26428028100
Researcher ID
K-7483-2019

Research Output

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  • Publication
    A Comprehensive Review of Midrange Wireless Power Transfer Using Dielectric Resonators
    ( 2021-01-01)
    Azuwa Ali
    ;
    Mohd Najib Mohd Yasin
    ;
    Faiz Wan Ali W.F.
    ;
    Norsuria Mahmed
    ;
    Kamarudin M.R.
    ;
    Ismahayati Adam
    ;
    Muzammil Jusoh
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Khor Shing Fhan
    ;
    Nurulazlina Ramli
    ;
    Norshamsuri Ali @ Hasim
    Magnetic resonant coupling (MRC) is one of the techniques that are widely used in wireless power transfer (WPT) systems. The technique is commonly used for enhancing distance while maintaining power transfer efficiency (PTE). Many studies have investigated new technologies to extend the distance of MRC while maintaining high PTE values. The most promising technique to date in MRC is the addition of a resonator between the transmitter and the receiver coil. The implementation of the resonator varies based on different designs, sizes, and material types, although the outcomes remain unsatisfactory. By introducing dielectric material resonators, PTE can be improved by lowering the ohmic loss which becomes a problem on conventional resonators. This study presents a general overview on the use of dielectric material as a resonator in MRC WPT technology and its technological development. The basic operation of MRC WPT is summarized with up-to-date technical improvements related to dielectric material as a resonator in the field of WPT. An overview of the current limitations and challenges of this technique is also highlighted in this study.
      1
  • Publication
    Investigation on Wearable Antenna under Different Bending Conditions for Wireless Body Area Network (WBAN) Applications
    ( 2021-01-01)
    Ismahayati Adam
    ;
    Kamarudin M.R.
    ;
    Rambe A.H.
    ;
    Haris N.
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Wan Zuki Azman Wan Muhamad
    ;
    Arif Mawardi Ismail
    ;
    Muzammil Jusoh
    ;
    Mohd Najib Mohd Yasin
    This paper analysed the effects of bending on the performance of a textile antenna wherein the antenna under test was made of felt substrate for both industrial, scientific, and medical (ISM) band and WBAN applications at 2.45 GHz. Moreover, the conductive material was used for the patch, and the ground plane used a 0.17 mm Shieldit textile. Meanwhile, the antenna structure was in the form of rectangular, with a line patch in between elements to abate the mutual coupling effect. The measured operating frequency range of the antenna spanned from 2.33 GHz to 2.5 GHz with a gain of 4.7 dBi at 2.45 GHz. In this paper, the antenna robustness was examined by bending the structure on different radii and degrees along both X- and Y-axis. Next, the effects on return loss, bandwidth, isolation, and radiation characteristics were analysed. This paper also discovered that the antenna's performance remained acceptable as it was deformed, and the measured results agreed well with the simulation.
      3  25
  • Publication
    Feasibility study on RF energy harvesting in Malaysia
    ( 2017-01-01)
    Ismahayati Adam
    ;
    Mohd Najib Mohd Yasin
    ;
    Mohd Fareq Abd Malek
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Shakhirul Mat Salleh
    ;
    Mohammad Shahrazel Razalli
    Worlds are looking for a renewable energy to replace current energy sources. Solar and wind renewable energy has been deployed for some years as one renewable energy in a few countries in a large scale. For a small scale renewable energy, the development of electromagnetic energy harvesting has good potential as one of the sources of renewable energy since the electromagnetic energy is available all the time and everywhere, unlike other renewable energy (e.g., solar, wind, thermal and ocean wave). First step of feasibility of scavenging an RF energy is investigated through power density measurement in urban and semi-urban area. An average power of −13.33 dBm (UMTS band) measured in urban environment.
      41  3
  • Publication
    Mutual Coupling Suppression in Wearable MIMO Antenna for On/Off-Body WBAN Applications
    ( 2021-03-01)
    Ismahayati Adam
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Mohd Najib Mohd Yasin
    ;
    Muhammad Nazrin Mohd Nasrol
    A 2x1 wearable multiple-input-multiple-output (MIMO) antenna with line patch as mutual coupling suppression is presented. The proposed MIMO antenna is based on a simple rectangular structure that works at 2.45 GHz frequency. The patches are designed using ShieldIt textiles and are placed to a very closed (0.1λ) gap. The results show that the suppression in the mutual coupling of 5 dB (from-20 dB to-25dB), reduced by 25% after the line patch is inserted in between patches. On a positive note, an improvement in the antenna gain, from 4.4 dB to 4.7dB is achieved. On top of that, the performance of the reflection coefficient (S11) and the antenna impedance bandwidth is preserved. Important diversity performance parameter for MIMO antenna such as ECC, diversity gain and MEG results are found to be in an acceptable limit.
      1  16
  • Publication
    UWB Antenna with Artificial Magnetic Conductor (AMC) for 5G Applications
    ( 2020-01-01)
    Syuhaimi Kassim
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Abdulmalek M.
    ;
    R Badlishah Ahmad
    ;
    Jamaluddin M.H.
    ;
    Muzammil Jusoh
    ;
    Mohsin D.A.
    ;
    Yahya N.Z.
    ;
    Wee Fwen Hoon
    ;
    Ismahayati Adam
    ;
    Rani K.N.A.
    This paper presents the design of an ultra-wideband (UWB) antenna for Internet of Things (IoT) applications that operate within 5G operating frequencies. One of the IoT-based devices’ architecture is wireless body area networks (WBANs). WBAN allows computer device to communicate with human body signal by trading digital information like electrical conductivity. Fifth generation (5G) is the state-of-the-art generation mobile communication. A higher data speed it offers will improve data communication efficiency in WBAN system. One of the biggest challenges foreseen for the wearable UWB antenna is the antenna bandwidth. The challenge is to warrant a wideband performance throughout the operating frequency, and a trade-off with a high dielectric in proposed substrate is essential. This paper presents design and parametric analysis of an antenna using a typical industry-preferred Rogers material (RO4350B) substrate with wider bandwidth as compared to 5G frequencies, 10.125–10.225 GHz. This paper also exhibits bandwidth improvement with the presence of artificial magnetic conductor (AMC) as a metasurface. A typical UWB patch antenna was initially designed before being integrated with AMC through a parametric analysis. This paper analyzes the frequency, gain, directivity and antenna efficiency before and after optimization. This paper successfully demonstrates a slotted Y-shaped antenna design with coplanar waveguide (CPW) using a Rogers material (RO4350B) as a substrate and the bandwidth improvement by 15.6% with the AMC as a metasurface.
      32  2
  • 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
    Analysis of Symmetric Two and Four-coil Magnetic Resonant Coupling Wireless Power Transfer
    ( 2022-04-01)
    Ali A.
    ;
    Mohd Najib Mohd Yasin
    ;
    Rambe A.H.
    ;
    Ismahayati Adam
    ;
    Ramli N.
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Thennarasan Sabapathy
    ;
    Mohd Natashah Norizan
    ;
    Sobri S.A.
    This study examined the efficiency of power transfer for two-coil and four-coil spiral magnetic resonant coupling wireless power transfer (WPT) using distance to coil diameter (D/dm) ratio and reflection coefficient, S21 value. Adding resonators reduced the total resistance in the two-coil WPT system while increasing the S21 values of the whole system. A same-size spiral coil was proposed for the system and simulated using computer simulation technology (CST). A prototype with similar specifications for a four-coil design was implemented for verification. The proposed method yielded an optimal efficiency of 76.3% in the four-coil system, while the two-coil WPT yielded a 23.2% efficiency with a 1.33 D/dm ratio.
      2  30
  • Publication
    1×4 Patch Array All-Textile Antenna for WLAN Applications
    ( 2020-09-28)
    Mashaghba H.A.
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Ping Jack Soh
    ;
    Abdulmalek Mohamedfareq
    ;
    Ismahayati Adam
    ;
    Muzammil Jusoh
    ;
    Mohd Najib Mohd Yasin
    ;
    Thennarasan Sabapathy
    ;
    Khairul Najmy Abdul Rani
    This paper proposes the design of 1×4 patch array all-Textile antenna for Wireless Local Area Networks (WLAN) applications. The wearable antenna needs to have low profile and lightweight since such antenna is intended to operate in the vicinity of the human body. The key parameters are studied to determine their effects towards the performance of the antenna. The proposed design uses ShieldIt as the top radiator and ground plane, while fabric Felt is used as a substrate, sandwiched between the top radiator and ground plane.The obtained results show that there is improvement in the proposed array antenna in terms of gain enhancement and impedance bandwidth, maximum up to 143.6% and 19.08%, respectively, against single patch structure.
      4  47
  • Publication
    5G Millimeter Wave Wearable Antenna: State-Of-the-Art and Current Challenges
    ( 2021-01-01)
    Hasliza A Rahim @ Samsuddin
    ;
    Mashagba H.A.
    ;
    Yahaya N.Z.
    ;
    Mohd Najib Mohd Yasin
    ;
    Jamaluddin M.H.
    ;
    Muzammil Jusoh
    ;
    Thennarasan Sabapathy
    ;
    Ismahayati Adam
    ;
    Abdulmalek M.
    Fifth Generation (5G) is the next evolution of mobile communication that will provide seamless and massive high speed connectivity to the society. Paralleled with the rise of 5G, it is foreseen that wearable devices particularly wearable antenna will be the significant end node for wearable devices in Millimeter Wave (mmWave) frequency bands. Thus, this paper discusses the new development of the 5G sub-6 GHz and mmWave wearable antenna, introduces the research results of the 5G mmWave wearable antenna in recent years, and addresses the key challenges in the development trend of the development trend of the 5G mmWave wearable antenna.
      2  14
  • Publication
    Triple-Band Circularly Polarized Dielectric Resonator Antenna (DRA) for Wireless Applications
    ( 2023-01-01)
    Azuwa Ali
    ;
    Mohd Najib Mohd Yasin
    ;
    Ismahayati Adam
    ;
    Rambe A.H.
    ;
    Jamaludin M.H.
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Cengiz C.
    ;
    Razak M.I.S.A.
    This paper proposes a new dielectric resonator antenna (DRA) design that can generate circularly polarized (CP) triple-band signals. A triple-band CP DRA antenna fed by a probe feed system is achieved with metal strips structure on side of DRA structure. The design start with conventional rectangular DRA with F shaped metal strips on DRA structure alongside the feed. Then, the F metal strip is enhanced by extending the length of the metal strip to obtain wider impedance bandwidth. Further improvement on the antenna performance is observed by improvised the conventional DRA structure. The method of removing part of DRA bottom resulted to higher antenna gain with triple band CP. The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The CP BW values recorded by the proposed antenna were ∼ 11.27% (3.3–3.65 GHz), 12.18% (4.17–4.69 GHz), and 1.74% (6.44–6.55 GHz) for impedance-matching BW values of 35.4% (3.3–4.69 GHz), 1.74% (5.36–5.44 GHz), and 1.85% (6.41–6.55 GHz) with peak gains of 6.8 dBic, 7.6 dBic, and 8.5 dBic, respectively, in the lower, central, and upper bands. The prototype of the proposed antenna geometry was fabricated and measured. A good agreement was noted between the simulated and the measured results.
      3  25