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Author: search.filters.author.Luadang, BanchaSubject: search.filters.subject.wideband antenna

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    Wideband Bidirectional Circularly Polarized S-Slot Antenna with Dielectric Superstrate
    (2024-01-01)
    Luadang, Bancha
    ;
    Janpangngern, Pisit
    ;
    Phongcharoenpanich, Chuwong
    This paper presents the design of a circularly polarized (CP) wideband S-slot antenna with a bidirectional radiation pattern, using a dielectric superstrate (DS) to increase the gain. The antenna achieves an enhance axial ratio (AR) bandwidth and reduced back lobe of radiation pattern. The S-slot antenna is positioned midway between a rectangular dielectric superstrate and an S-slot radiating element, which has a dielectric constant of εr = 4.3. The DS acts as a lens, refracting the electric field to combine the antenna beam and increase the antenna gain. For performance evaluation, the S-slot radiating element without the DS was compared to the proposed antenna. The antenna size is optimized for a center frequency of 5.5 GHz. The square DS contributes significantly to the bandwidth ratio, achieving an axial ratio AR ≤ 3 dB across the design frequency range (|S11| ≤ -10 dB) of 4.0-6.25 GHz. This antenna design is suitable for wireless communications and 5G sub-6 GHz applications, such as in long bridge/tunnel areas, coal mines communications, radio frequency identification (RFID) systems, and various wireless communication systems.
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    Bandwidth Enhancement of a Circularly Polarized Spiral Antenna using a Circular EBG Reflector
    (2023-01-01)
    Luadang, Bancha
    ;
    Janpangngern, Pisit
    ;
    Phongcharoenpanich, Chuwong
    ;
    Chudpooti, Nonchanutt
    This paper describes the bandwidth enhancement of a circularly polarized (CP) spiral antenna using a circular electromagnetic band-gap (EBG) reflector for satellite communications and other wireless applications. The spiral antenna is placed at the front, and at the bottom is a circular EBG reflector with high-impedance surface properties. For comparison, circular EBG reflector was studied in comparison with circular PEC reflector. The antenna height from the bottom of the circular EBG reflector to the spiral antenna is small: 0.1 wavelengths at the lowest design frequency of 1.3 GHz. The circular EBG reflector contributes to a constant input impedance and small axial ratio (AR) throughout the design frequency range of 1.5–9.0 GHz (143%). The results of the analysis were verified by the measured results of the prototype antenna.
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    Portable Wideband Directional Antenna Scheme with Semicircular Corrugated Reflector for Digital Television Reception
    (2022-07-01)
    Luadang, Bancha
    ;
    Pukraksa, Rerkchai
    ;
    Janpangngern, Pisit
    ;
    Pookkapund, Khanet
    ;
    Dentri, Sitthichai
    This research proposed a portable wideband horizontally-polarized directional antenna scheme with a radome for digital terrestrial television reception. The operating frequency band of the proposed antenna scheme is 470–890 MHz. The portable antenna scheme was an adaptation of the Yagi-Uda antenna, consisting of a folded bowtie radiator, a semicircular corrugated reflector, and a V-shaped director. Simulations were carried out, and an antenna prototype was fabricated. To validate, experiments were undertaken to assess the antenna performance, including the impedance bandwidth (|S<inf>11</inf>| ≤ −10 dB), gain, and unidirectionality. The measured impedance bandwidth was 75.93%, covering 424–943 MHz, with a measured antenna gain of 2.69–4.84 dBi. The radiation pattern was of unidirectionality for the entire operating frequency band. The measured xz- and yz-plane half-power beamwidths were 150°, 159°, 160° and 102°, 78°, 102° at 470, 680, and 890 MHz, with the corresponding cross-polarization below −20 dB and −40 dB. The radome had a negligible impact on the impedance bandwidth, gain, and radiation pattern. The power obtained for the outdoor test, at 514 MHz, was 38.4 dBµV (−70.4 dBm) with a carrier-to-noise ratio (C/N) of 11.6 dB. In addition, the power obtained for the indoor test was 26.6 dBµV (−82.2 dBm) with a C/N of 10.9 dB. The novelty of this research lies in the concurrent use of the Yagi-Uda and bowtie antenna technologies to improve the impedance bandwidth and directionality of the antenna for digital terrestrial television reception.