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    Design 2.4/5.8 GHz microstrip-to-coplanar strip transition
    (2007-12-01)
    Meelarpkit, Kumron
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    ; ;
    Chongcheawchamnan, Mitchai
    A 2.4/5.8 GHz microstrip (MS)-to-coplanar stripline (CFS) transition (industrial-scientific-medical bands) is presented in this paper. The transition can operate at two bands simultaneously with a stepped impedance transformer and stepped impedance open stub. The circuit is proven with a design on RF060 substrate. Simulated and experimental results of the transitions connected in back-to-back style are in good agreement. The back-to-back transition exhibits return and insertion losses, which are better than 15 dB and 3 dB, respectively.
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    Heuristic UTD solution for antennas near a complex platform
    (2019-01-01)
    Pimpatang, Awika
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    Lertwiriyaprapa, Titipong
    ;
    This paper is aimed at developing an approximate and relatively simple but closed-form uniform geometrical theory of diffraction (UTD) solution for describing the radiated and scattered fields by an antenna near a complex platform consisting of a three-dimensional (3-D) thin material-coated metallic surface, including edges and corners. Unlike the previous works that consider primarily plane wave scattering, the developed solution can also treat radiation/scattering problems of antennas near finite material-coated metallic surfaces which are composed of edges and corners. The developed solution, which is formulated by using a heuristic approach, recovers the proper local plane wave Fresnel reflection coefficient. In addition, the developed UTD-diffracted fields will satisfy the radiation condition, boundary conditions on the conductor. The accuracy of the developed solution is verified by comparing with simulation results from a computer software. It is found that the results from our developed solution agree well with those of references. However, some small discrepancies occur but it is good enough for engineering applications. The proposed solution can be very useful for antenna engineers to design multiple antennas with an electrically large complex material-coated platform.
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    EBG-backed ultrawideband circularly polarized Archimedean spiral antenna scheme for IoT applications
    (2025-12-01)
    Luadang, Bancha
    ;
    Ainthachot, Chalanthon
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    Janpangngern, Pisit
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    Pookkapund, Khanet
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    Torrungrueng, Danai
    This research proposes a low-profile ultrawideband circularly polarized Archimedean spiral antenna with an electromagnetic band gap (EBG)-backed structure. The proposed antenna scheme consists of an upper-layer spiral radiator, a microstrip tapered balun, and a lower-layer high-impedance circular EBG reflector of three concentric rings of trapezoid-shaped unit cells. The antenna scheme can achieve a significant profile reduction, with a total height of 0.1 wavelengths at the lowest operational frequency. The integration of the EBG reflector improves the radiation characteristics and antenna gain, achieving a maximum gain of 9.87 dBic at 6.90 GHz. The EBG reflector also improves impedance matching and axial ratio (AR) over the 1.5–8.75 GHz frequency range, achieving a wide AR bandwidth of 141.46%. The novelty of this work lies in the integration of Archimedean spiral antenna with high-impedance EBG reflector of trapezoid-shaped unit cells to enhance the impedance and AR bandwidths without increasing the overall antenna profile. Essentially, the proposed antenna scheme is suitable for broadband communication systems that require ultrawide bandwidth, circular polarization, and a small form factor.
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    A unidirectional antenna using circular disc monopole excited circular ring above cylindrical reflector
    (2008-12-01)
    Vongsack, Souphanna
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    ;
    Kosulvit, Sompol
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    Wakabayashi, Toshio
    The objective of this paper is to propose a unidirectional antenna using circular disc monopole excited circular ring above cylindrical reflector to cover the frequency of 3.1-10.6 GHz for ultra-wideband (UWB) applications. The simulated results are presented ultra-wideband performance of this antenna by using Computer Simulation Technology (CST®). The simulated results verified that the proposed antenna radiates unidirectional pattern. Moreover, the antenna design is described in terms of return loss/impedance bandwidth and radiation pattern. The return loss of better than 10 dB covers the frequency range from 2.46 to 12.41 GHz. The proposed antenna has a unidirectional pattern with the gain of 9.98 dBi at 3 GHz, 11.56 dBi at 7 GHz and 11.59 dBi at 11 GHz from the simulated results. Moreover, the design of this antenna is simple. Therefore, proposed antenna is suitable for many applications in long and narrow path service cell. © 2008 IEEE.
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    Broadband Two-Array Metasurface-Gridded MIMO Antenna with Dual-CP Bi-Directional Capabilities
    (2025-01-01)
    Supreeyatitikul, Nathapat
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    Kakhong, Khwanlada
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    Prasong, Pusit
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    ;
    Konpang, Jessada
    This study presents a novel two-array MTS-gridded MIMO antenna with dual circular polarization (CP) bidirectional capabilities for full-duplex communications. The proposed antenna consists of two mirrored clusters, each comprising a single-element antenna formed by a 3 × 4 MTS-gridded element array, a circular patch, and a ground plane. The antenna demonstrates a wide measured return loss bandwidth (RLBW) of 56.46% (5 - 8.67 GHz), axial ratio bandwidth (ARBW) of 18.15% (6.26 - 7.44 GHz), and strong isolation below -22 dB. Peak gains of 6.5 dBic and 6.55 dBic were observed at 6.6 GHz and 6.54 GHz for Ports 1 and 2, respectively. Furthermore, the low envelope correlation coefficient (< 0.005) and high diversity gain (> 9.985 dB) validate its effectiveness for multi-port applications. The bidirectional radiation pattern and dual circular polarization support simultaneous transmission and reception, making the design well-suited for full-duplex MIMO operation.
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    Dual-band dual-pattern truncated-corners microstrip antenna for GPS and WiFi applications
    (2015-04-22)
    Chan-Arpas, Patthareeya
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    Dentri, Sitthichai
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    This paper proposes a dual-frequency antenna for vehicles. The antenna structure consists of single patch and single feed. It is operated at the center frequency of GPS system at 1.575 GHz with circular polarization and 2.45 GHz for Wireless Local Area Networks (WLAN) with linear polarization. At 1.575 GHz, S<inf>11</inf>≤-10 dB can cover the frequency from 1.51 to 1.61 GHz. At 2.45 GHz, S<inf>11</inf>≤-10 dB can cover from 2.45 to 2.48 GHz, respectively. The axial ratio bandwidth (AR < 3 dB) is ranged from 1.56 to 1.59 GHz. The measured gains are 4.74 dBic and 2.08 dBi at center frequency, respectively. The half-power beamwidths (HPBW) in xz-and yz-planes are 85 and 85 degrees and the AR beamwidths in xz-and yz-planes are 180 and 200 degrees, respectively.
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    Broadband planar dipole array Antenna with double C-shaped slit elements for digital TV broadcasting transmission
    (2016-06-01)
    Osklang, Pracha
    ;
    This research has proposed a planar rectangular dipole antenna enclosed in double C-shaped parasitically slit elements (i.e., radiator element) on a double-cornered reflector for bandwidth enhancement. In the study, simulations were first carried out to determine the optimal parameters of the radiator element and then a radiator element prototype was fabricated and mounted onto a double-cornered aluminum reflector. The simulated and measured |S<inf>11</inf>|<–10 dB of the antenna element covered the frequency ranges of 451–901 MHz (66.6%) and 455–886 MHz (64.3%), respectively. The gain was enhanced by the subsequent deployment of multiple radiator elements to fabricate a four-element vertically array antenna on an elongated double-cornered reflector. The simulated and measured |S<inf>11</inf>|<−10 dB of the array antenna, respectively, covered the 410–991 MHz (82.9%) and 415–886 MHz (72.4%) frequency ranges. The proposed array antenna radiates unidirectionally across the DTV frequency band with a measured front-to-back ratio and cross polarization >20 and <−23 dB, respectively. The simulated and measured half-power beam widths in the E and H planes were respectively 56° ± 13° and 20° ± 6°; and 57° ± 13° and 21° ± 6°. In addition, the simulated and measured gains of the array antenna were 12.8–16.4 dBi and 11.3–15.8 dBi along the 470–862 MHz frequency range. This proposed array antenna is thus suitable for DTV broadcasting transmission. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:466–478, 2016.
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    Metasurface-based Circularly Polarized Dual-Port MIMO Antenna for C-band Uplink Applications
    (2022-01-01)
    Supreeyatitikul, Nathapat
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    Boonpoonga, Akkarat
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    The rectangular-shaped metasurface (MTS)- based circularly polarized (CP) dual-port MIMO antenna was proposed. The proposed rectangular-shaped MTS-based CP dual-port MIMO antenna included two substrate layers (upper and lower). The periodic 4×4 rectangular-shaped MTS elements on the upper layer functioned as CP polarizers. Also, the lower substrate layer comprised the microstrip probe feed and ground plane which generated a linearly polarized (LP) wave. The proposed rectangular-shaped MTS-based CP dual-port MIMO antenna at 5.3 GHz achieved impedance bandwidth (IBW) of 30.9% (4.86 - 6.5 GHz) and axial ratio (ARBW) of 14% (5.16 - 5.9 GHz). The maximum gain was 7.3 dBi at 5.1 GHz. The ECC was lower than 0.002, and DG was greater than 9.98 dB between entire frequency ranges. The direction of the radiation was right-hand circular polarization (RHCP). The dimension of proposed rectangular-shaped MTS-based CP dual-port MIMO antenna was 1.342λ0 × 0.652λ0 × 0.0372λ0.
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    Compact dual-band I-shaped patch antenna with longitudinal strip on inverted-T ground plane
    (2014-01-01)
    Chawanonphithak, Yuktitath
    ;
    This paper presents a compact dual-band I-shaped patch antenna with longitudinal strip on inverted-T ground plane for wireless local area network (WLAN) applications over the frequency band of 2.400-2.484 GHz and 5.150-5.350 GHz. The I-shaped patch antenna and inverted-T ground plane are etched onto a piece of printed circuit board (PCB) with an overall size of 40 mm × 60 mm × 1.6 mm. It is excited by strip line to match impedance with a 50 ω transmission line. The measured results show that the miniaturized antenna achieves a broad operating bandwidth of 2.26-2.89 GHz and 4.92-5.83 GHz for S<inf>11</inf><-10 dB and omnidirectional radiation pattern. The measured gains of the antenna at 2.4 GHz and 5.2 GHz frequencies are 1.90 dBi and 3.45 dBi, respectively. © 2014 IEEE.