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Author: search.filters.author.Kuse, Ryuji

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    Omnidirectional Circularly Polarized Monopole Antennas on Artificial Magnetic Conductor Ground Plane
    (2024-01-01)
    Janpangngern, Pisit
    ;
    Kuse, Ryuji
    ;
    Phongcharoenpanich, Chuwong
    ;
    Fukusako, Takeshi
    This research proposes omnidirectional circularly polarized monopole antennas (OCPA) with single-annular (SA-AMC) and dual-annular artificial magnetic conductor (DA-AMC) ground planes. The aim of the proposed antenna scheme is to circumvent the design rigidity of conventional OCPA whose inherent shortcoming is fixed bottom ground plane size. The OCPA with SA-AMC ground plane consists of a monopole element, four diagonally adjoined parasitic elements to convert linear to circular polarizations, and an SA-AMC ground plane. The OCPA with DA-AMC ground plane consists of a monopole element, four diagonally adjoined parasitic elements, and a DA-AMC ground plane. Unlike the conventional OCPA, the bottom ground plane radius (R-{text {g}}) of the OCPA with SA- and DA-AMC ground planes can be varied between 18.4 - 188.4 mm; and 29.2 - 119.2 mm, respectively, without affecting the omnidirectionality and impedance and axial ratio (AR) bandwidths of the OCPA. Furthermore, the SA- and DA-AMC ground planes effectively improve the impedance (left |{{S-{11}}}right | leq -,10 dB) and AR bandwidths (AR leq 3,{} dB) while reducing leakage current on the coaxial feeder cable. The measured left |{{S-{11}}}right | and AR bandwidths of the OCPA with SA-AMC ground plane, given the optimal R-{g} of 18.4 mm, are 8.08% (5.34 - 5.79 GHz) and 4.38% (5.36 - 5.60 GHz), while those of the OCPA with DA-AMC ground plane, given the optimal R-{text {g}} of 29.2 mm, are 14.37% (5.10 - 5.89 GHz) and 19.85% (4.90 - 5.98 GHz). The novelty of this research lies in the use of SA- and DA-AMC structures to circumvent the design rigidity of the conventional OCPA. Essentially, the integration of the AMC structures offers design flexibility in the realization of OCPA.
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    Broadband linear-to-circular polarisation conversion using the diamond-shaped reflecting metasurface
    (2020-07-29)
    Chaihongsa, Warangkana
    ;
    Kuse, Ryuji
    ;
    Furuya, Koichi
    ;
    Phongcharoenpanich, Chuwong
    ;
    Fukusako, Takeshi
    To overcome the narrow axial ratio (AR) bandwidth inherent in conventional linearly to circularly polarised converters, this research proposes a metasurface (MS) with a diamond-shaped configuration that can mitigate the effect of surface wave (SW) along the MS edge and achieve a wider 3 dB AR bandwidth. The diamond-shaped MS structure is realised by slanting a square MS by 45°, and it consists of constituent unit cells of rectangular and arbitrary shapes. The rectangular unit cells are positioned 45° to the square dielectric substrate, and the unit cells along the MS edge are partially cut into arbitrary shape to be perfectly aligned along the edge. The 3 dB AR bandwidths and degradation of the MS are characterised by SW and magnetic current distribution. Simulations are carried out and an MS prototype is fabricated to verify the results. The effects of partially cut unit cells (PCUCs) along the MS edge on the SW are characterised. The simulation and measured 3 dB AR bandwidths of the diamond-shaped MS are 37.6 and 28.8%, respectively. The novelty of the proposed diamond-shaped MS polarisation converter lies in the implementation of arbitrary-shaped PCUCs and the use of the diamond-shaped configuration in place of conventional square geometry to realise wider AR bandwidth.
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    Broadband circularly polarized microstrip patch antenna using circular artificial ground structure and meandering probe
    (2020-01-01)
    Pookkapund, Khanet
    ;
    Sakonkanapong, Arnon
    ;
    Kuse, Ryuji
    ;
    Phongcharoenpanich, Chuwong
    ;
    Fukusako, Takeshi
    To enhance axial ratio (AR) bandwidth, this research proposes a circularly polarized (CP) single-fed microstrip patch antenna using a circular artificial ground structure (AGS) and meandering probe. To achieve broader AR bandwidth, the circular AGS is populated with rectangular unit cells and partially cut unit cells along the circular contour, while the meandering probe is used to improve the impedance bandwidth. Simulations are performed and results compared with that of conventional rectangular-AGS antenna. The simulation results show that the circular-AGS antenna, given 62 mm circular ground plane, achieves broader impedance (5.12 - 9.00 GHz and 54%), AR (5.21 - 8.27 GHz and 45%) and gain bandwidths (3.85 - 7.00 GHz and 58.06%), in comparison with the rectangular-AGS antenna (4.50 - 7.45 GHz and 49%; 4.52 - 7.42 GHz and 21%; and 4.00 - 6.80 GHz and 51.58% for impedance, AR and gain bandwidths). The circular-AGS antenna is capable of converting linear polarization in the off-axial ratio band into circular polarization. To verify, a circular-AGS antenna prototype is fabricated and experiments undertaken. The experimental impedance, AR and gain bandwidths of the circular-AGS antenna are 47.82% (5.17 - 8.42 GHz), 43.81% (5.24 - 8.17 GHz) and 60.74% (3.75 - 7.00 GHz). The proposed circular-AGS antenna can achieve broader AR bandwidth and is thus ideal for broadband CP applications. The novelty of this research lies in the use of circular AGS to effectively enhance AR bandwidth, as opposed to rectangular AGS which is conventionally used in CP polarizers.