Artículos de revista DIEC - IEKS Aldizkari artikuluak

Permanent URI for this collection

http://hdl.handle.net/2454/29500

Browse

Browsing Artículos de revista DIEC - IEKS Aldizkari artikuluak by Author "Ahmad, Jawad"

Now showing 1 - 2 of 2
  • Thumbnail Image
    PublicationOpen Access
    Design and analysis of a low profile millimeter-wave band Vivaldi MIMO antenna for wearable WBAN applications
    (IEEE Xplore Digital Library, 2024) Ahmad, Jawad; Hashmi, Mohammad; Bakytbekov, Azamat; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
    The development of a reliable Wireless Body Area Network (WBAN) relies significantly on the quality of wearable antennas. Therefore, this paper proposes a low-profile four-element Multi-Input- Multi-Output (MIMO) antenna for wearable millimeter-wave (mm-wave) WBAN applications. The MIMO antenna structure incorporates a standardVivaldi antenna and a frequency-selective surface that encompasses the 28 GHz and 30 GHz of the mm-wave band with a 36.44% fractional bandwidth. It offers inter-element isolation of less than -20 dB in a compact space of 16 x 20 mm2. Conformability analysis, along with testing on Gustav’s model chest, hand, and leg, was evaluated in terms of the antenna impedance bandwidth, gain, efficiency, and radiation pattern. The simulated characteristics of the MIMO antenna were tested through measurements in free space and on the human body using a prototype of the antenna. Furthermore, the MIMO antenna exhibits a low envelope correlation coefficient of less than 0.24, high diversity gain of greater than 9.95 dB, and an acceptable total active reflection coefficient of less than -10 dB. To ensure safety, the Specific Absorption Rate (SAR) analysis revealed acceptable levels of 0.397 and 0.267 (W/kg) at 28 GHz and 30 GHz, respectively. The proposed MIMO design is suitable for wearable WBAN applications owing to its small size, consistent gain, and compatibility with the human body in terms of a constant impedance bandwidth and end-fire radiation pattern.
  • Thumbnail Image
    PublicationOpen Access
    A hybrid technique for mutual coupling reduction in a compact dual-band millimeter-wave MIMO antenna
    (IEEE, 2025-07-01) Ahmad, Jawad; Hashmi, Mohammad; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
    This letter reports a hybrid approach employing metallic vias and metasurface for mutual coupling reduction in a MIMO antenna at mmWave frequencies. Initially, a dual-band coaxial-fed antenna, operating at 27 GHz and 28 GHz, is designed using modified K-shaped patch arms with a tapered profile which is then used to develop a four-element dual-band MIMO array. Subsequently, metallic vias are incorporated to suppress surface wave-induced coupling. Finally, metasurface slab is integrated to mitigate near-field interactions. The proposed design achieves an impedance bandwidth of 26.75-27.28 GHz and 27.77-28.19 GHz, with coupling levels below 30 dB, and broadside radiation patterns with respective peak gains of 6.52 dBi and 6.74 dBi. Furthermore, the proposed design exhibits an envelope correlation coefficient (ECC) of less than 0.05 for isotropic and less than 0.25 for Gaussian environments. An excellent agreement between the experimental and simulation results validate the proposed design approach.