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All Journal International Journal of Electrical and Computer Engineering Indonesian Journal of Electrical Engineering and Computer Science
Yoshihide Yamada
Universiti Teknologi Malaysia
Computer Science & IT Electrical & Electronics Engineering

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 1 
Radiation Pattern Performance of Unequally Linear Arrays with Parasitic Element Noor Ainniesafina Zainal; Muhammad Ramlee Kamarudin; Yoshihide Yamada; Norhudah Seman
Indonesian Journal of Electrical Engineering and Computer Science Vol 6, No 1: April 2017
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v6.i1.pp110-115

Abstract

For next generation of 5G mobile base station antennas, multibeam, multifrequency and low sidelobe characteristics requested. Simplify the feeding network will contribute a low feeder loss and frequency dependent. From the previous research by the author, low sidelobe level reported by density tapered array configuration from -13 dB to -16 dB and the result maintained for wideband operation frequency at 28 GHz, 42 GHz, and 56 GHz. However, the grating lobe has occurred due to element spacing larger than a wavelength of higher frequency (56 GHz). In this paper, an investigation was made of the performance of radiation pattern for unequally microstrip linear array antenna in frequency 42 GHz and 56 GHz by loading parasitic elements. The effect of parasitic element to the impedance, gain, and sidelobe level of unequally microstrip linear spaced tapered array also examined. The design has been simulated using Ansoft High Frequency Structural Simulator (HFSS) ver 16.0.
Higher-order Mode Rectangular Dielectric Resonator Antenna for 5G Applications Nor Hidayu Shahadan; Muhammad Ramlee Kamarudin; Mohd Haizal Jamaluddin; Yoshihide Yamada
Indonesian Journal of Electrical Engineering and Computer Science Vol 5, No 3: March 2017
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v5.i3.pp584-592

Abstract

The excitation of the higher-order mode, in rectangular dielectric resonator designed was explored to enhance the antenna gain and detailed elaboration is presented in this paper. The antenna was fed by a 50Ω microstrip line through an aperture cut in the ground plane. Besides avoiding spurious radiation, this feeding technique gives flexibility in controlling the amount of coupling in order to reduce the Q-factor in the higher-order mode RDRA. A design was developed and subsequently simulated using Ansoft HFSS ver 16.0 by utilizing Duroid 5880 dielectric substrate with a thickness (ts) of 0.254 mm, a permittivity (εs) of 2.2 and a loss tangent (δ) of 0.001 at 15 GHz. The higher-order mode, RDRA achieved the measured gain at 9.76 dBi and the measured impedance bandwidth as much 2.5 GHz which is 4.7% more compared to the fundamental mode. The result should be considered suitable for 5G applications.
Performance analysis of patch antenna for underwater wireless communication in seawater Siti Harliza Mohd Razali; Razali Ngah; Yoshihide Yamada; Kamilia Kamardin
Indonesian Journal of Electrical Engineering and Computer Science Vol 22, No 2: May 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v22.i2.pp857-865

Abstract

Underwater wireless communication in seawater is becoming more interesting and challenging in recent years. The development of antenna for underwater wireless communication in seawater at 900 MHz UHF range frequency is implemented by using patch antenna. In this paper, the antennas were designed using FEKO, an electromagnetic simulation software, and a suitable size for rectangular patch antenna for seawater application was developed to study the relevance between λ0 with W and L in seawater. The difference between the patches in free space and seawater was the L size, which was slightly bigger, about 0.9 mm, than free space size. But the gain for patch antenna in seawater was found at -2.51 dBi, lower than patch antenna in free space, which was 5.76 dBi due to the path loss in seawater. This shows that attenuation happened, and a better antenna will be design. The one that has better gain, which is around above 2 dBi in seawater, in order to get better performance antenna in seawater environment.
Near-field microwave focusing evaluation of dielectric lens antenna for human body model Amirah Abd Rahman; Kamilia Kamardin; Yoshihide Yamada; Masaharu Takahashi
Indonesian Journal of Electrical Engineering and Computer Science Vol 29, No 1: January 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v29.i1.pp161-173

Abstract

Various small focus spot applicators are being investigated for hyperthermia therapy, which requires microwave concentration to heat tumors in the human body. Dielectric lens antenna is frequency independent and has strong focusing capability to achieve a very small focusing spot. In this paper, lenses with diameters of 30, 50 and 70 cm were designed to evaluate the size of the focal spot in the human body model. The electromagnetic simulator, FEKO was used to generate rays and near-field focusing data of dielectric lenses at a frequency of 2.45 GHz. The simulated focal spot sizes agreed well with the theoretical values. An analytical investigation into the power at the focal spot was conducted using the proposed power relations of the focused lens novel equation. The theoretical propagation loss is used to represent the power density degradation at the focal spot caused by microwave absorption by the human body. The simulation results of the focused lens in the human body indicated that the 30 cm lens achieved a larger focal spot with a greater focusing power, 0.714 mW compared to the 70 cm lens, which achieved a smaller focal spot but a lower focusing power, which was 0.393 mW.
Design of an axial mode helical antenna with buffer layer for underwater applications Afiza Nur Jaafar; Hajar Ja’afar; Yoshihide Yamada; Fatemeh Sadeghikia; Idnin Pasya Ibrahim; Mohd Khairil Adzhar Mahmood
International Journal of Electrical and Computer Engineering (IJECE) Vol 13, No 1: February 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v13i1.pp473-482

Abstract

Recently, there is an increasing demand for high-speed wireless communication network for short-range underwater communication. From previous research, most underwater antennas produced omnidirectional radiation pattern which has lower antenna gain. There are a few considerations that need to be taken if the antenna is designed to operate in water environment. This paper discusses the electromagnetic properties which affect the underwater antenna design. Physical properties such as electrical permittivity and conductivity of water contribute significant effect to the size of the antenna as it influences the behavior of electromagnetic signal that propagates in water. In this study, an axial mode helical antenna with waterproof container is presented which operates at 433 MHz. The axial mode helical antenna has circular polarization and is suitable to support wireless application which is surrounded by some obstruction. The proposed antenna produces a bidirectional radiation pattern by placing it into a waterproof casing. Good agreement between the simulation and measurement results validates the concept. However, a little discrepancy between the simulated and measured results may be attributed to the noise originated from the equipment and the environment.
Co-Authors Afiza Nur Jaafar Amirah Abd Rahman Fatemeh Sadeghikia Hajar Ja’afar Idnin Pasya Ibrahim Kamilia Kamardin Masaharu Takahashi Mohd Haizal Jamaluddin Mohd Khairil Adzhar Mahmood Muhammad Ramlee Kamarudin Muhammad Ramlee Kamarudin Noor Ainniesafina Zainal Nor Hidayu Shahadan Norhudah Seman Razali Ngah Siti Harliza Mohd Razali