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EBG-backed ultrawideband circularly polarized Archimedean spiral antenna scheme for IoT applications
(2025-12-01)
Luadang, Bancha
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Ainthachot, Chalanthon
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Janpangngern, Pisit
;
Pookkapund, Khanet
;
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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Ultrawideband Circularly Polarized Cavity-Integrated EBG-Backed Archimedean Spiral Antenna for IoT Applications
(2025-01-01)
Luadang, Bancha
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Janpangngern, Pisit
;
Phongcharoenpanich, Chuwong
This paper presents a compact ultrawideband circularly polarized Archimedean spiral antenna integrating a cavity-backed structure with a circular EBG reflector. The hybrid design enhances gain, suppresses backward radiation, and improves directivity, particularly below 3.0 GHz. The antenna covers 1.5-9.0 GHz with |S11| ≤ -10 dB and axial ratio ≤ 3 dB. Simulations show peak gain over 11.96 dBic at 6.5 GHz and a front-to-back ratio improvement due to the cavity. The proposed structure is well-suited for GPS, Wi-Fi, and IoT applications.
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Broadband unidirectional twin-element MIMO antenna scheme for mid-band 5G and WLAN laptops
(2024-12-01)
Luadang, Bancha
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Janpangngern, Pisit
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Pookkapund, Khanet
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Dentri, Sitthichai
;
Krairiksh, Monai
This research proposes a broadband unidirectional twin-element multiple-input-multiple-output (MIMO) antenna scheme for mid-band 5G and WLAN applications. The twin-element antenna scheme comprises two single-element antennas, and each single-element antenna consists of a T-shaped hemispherical feeding patch, left- and right-arm radiating patches, and a conjoined triangular ground plane. The twin-element MIMO antenna scheme is integrated with a laptop model functioning as the reflector. The measured impedance bandwidth (|S<inf>11</inf>|, |S<inf>22</inf>|≤ − 6 dB) are 55.32%, covering 3.4–6.0 GHz, and the measured mutual coupling (|S<inf>12</inf>|) is less than − 15 dB. The measured gain at the center frequency (4.5 GHz) is 4.585 dBi. Besides, the measured xz- and yz-plane cross-polarization levels are below − 25 dB and − 15 dB, respectively. The half-power beamwidth (HPBW) in the xz-plane at 3.5, 4.5, and 5.5 GHz are 99°, 92.8°, and 84.2°, and the corresponding HPBW in the yz-plane are 102°, 78°, and 102°. The measured xz- and yz-plane back lobe levels are below − 15 dB across the entire operating frequency band (3.5–5.5 GHz). The radiation pattern of the twin-element MIMO antenna scheme is of unidirectionality. Furthermore, the envelope correlation coefficient and diversity gain of the twin-element antenna scheme are < 0.001 and > 9.99 dB, respectively. The proposed broadband unidirectional twin-element MIMO antenna scheme is thus operationally suitable for mid-band 5G/WLAN communication systems. Essentially, this research is the first to propose a broadband twin-element MIMO antenna scheme for mid-band 5G/WLAN applications.
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Wideband Bidirectional Circularly Polarized S-Slot Antenna with Dielectric Superstrate
(2024-01-01)
Luadang, Bancha
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Janpangngern, Pisit
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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
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Janpangngern, Pisit
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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
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Pukraksa, Rerkchai
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Janpangngern, Pisit
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Pookkapund, Khanet
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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.
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Single-fed broadband CP bidirectional antenna with double-layer diagonally aligned plates for universal UHF-RFID applications
(2020-01-01)
Dentri, Sitthichai
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Pookkapund, Khanet
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Luadang, Bancha
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Akkaraekthalin, Prayoot
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Phongcharoenpanich, Chuwong
This research proposes a single-fed broadband circularly polarized (CP) bidirectional antenna operable in 840-960 MHz frequency band for readers of universal UHF-RFID applications. The proposed antenna is comprised of upper-layer conductor, lower-layer conductor, and wall patches. The upper-layer conductor consists of two diagonally aligned rectangular copper plates with a feeding gap at the center, and the lower-layer conductor is of two diagonally adjoined rectangular plates. The upper- and lower-layer conductors are adjoined with the wall patches. The diagonal alignment technique of the upper- and lower-layer plates was used to realize circular polarization and improve 3-dB axial ratio (AR) bandwidth. The double layers were deployed to improve impedance bandwidth (|S11| < -10 dB) and achieve bidirectional radiation pattern. The simulated impedance bandwidth and 3-dB AR bandwidth were 772.19-1014.6 MHz (27.13%) and 675-1000 MHz (38.80%), and the corresponding measured results were 759-1011 MHz (28.47%) and 648-1110 MHz (52.55%). The simulated LHCP/RHCP half-power beamwidth (HPBW), 3-dB AR beamwidth, and gain were 56° - 90°/54° - 92°, 60° - 104°, and 4.94 - 5.89 dBic, while the corresponding measured results were 52° - 98°/62° - 97°, 96° - 126°, and 4.28 - 5.72 dBic. As a result, the single-fed broadband CP bidirectional antenna is applicable to universal UHF-RFID readers. Besides, the novelty of this research lies in the use of diagonal alignment of conducting plates to achieve circular polarization and wider AR bandwidth.
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Wideband UHF Reflector Antenna for DVB Applications
(2019-12-01)
Osklang, Pracha
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Sakonkanapong, Arnon
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Dentri, Sitthichai
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Lertsakwimarn, Kittima
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Luadang, Bancha
This paper presents the design, measurement, and development of a bow tie wideband antenna using scutcheon shape with inductive-loaded for DVB applications. The antenna consists of 3 elements; a scutcheon bow tie radiator, a line inductive-loaded and a square reflector. The element of bow tie achieves a lower frequency of 470 MHz. The element of line inductive-loaded achieves an upper frequency of 860 MHz for |S11| of less than-10 dB. The measured results of the prototype antenna are good agreement. The impedance bandwidth of 81.27%, which covering a frequency range from 374 MHz to 886 MHz. The measured gains are flat around 7 dBi over the DVB band. The HPBW in the vertical and horizontal planes are 56.8° and 117.3° at frequency of 660 MHz.
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Measurement of Radiated Field from Transmitting Antennas Located in Various Environments
(2019-04-01)
Krairiksh, Monai
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Kittiyanpunya, Chainarong
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Limpiti, Thunyawat
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Tantisopharak, Tanawut
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Leekul, Prapan
In microcellular communications, the transmitting antennas can be installed at low heights above the ground. However, even for low elevation towers, installation cost is still high. One of the possible ways for the deployment of base station antennas is to install them near the ground in order to do away with the tower. The main purpose of this paper is to suggest installation of the radiating antennas near the ground and tilting their orientation toward the sky - a totally nonintuitive solution. It will be shown that such deployments have the potential of reducing slow fading and can further enhance the signal strength close to the radiating antenna. This paper provides measured data for the received fields to validate the theoretical conjecture of such a deployment in various environments. The measured results are presented for 245, 800, 1000, and 2400 MHz. It is illustrated that such an unorthodox deployment can result in a low cost for the installation of base station antenna as the towers are not necessary. This can be useful in restoring communications in emergency situations where minimum infrastructure exists.
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NFC-Enabled Far-Field Antenna on PET Flexible Substrate for 3G/4G/LTE Mobile Devices
(2019-01-01)
Luadang, Bancha
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Sakonkanapong, Arnon
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Dentri, Sitthichai
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Pansomboon, Rassamitut
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Phongcharoenpanich, Chuwong
This research presents a far-field (FF) antenna with near-field communication (NFC) capability for 3G/4G/LTE mobile devices. The integrated far- and near-field communication (FNFC) antenna was fabricated using conductive silver ink on polyethylene terephthalate (PET) flexible substrate. The FF segment of the antenna is operable in the frequency range of 1.8-2.1 GHz, and the NFC antenna is of dual loop and operable at 13.56 MHz. In the antenna realization, simulations were performed and, to validate, an antenna prototype was fabricated. The experimental results revealed that the FF antenna achieved an impedance bandwidth of 37% (1.52-2.21 GHz), given $\vert S_{11}\vert $ of less than -6 dB, with the minimum and maximum efficiency of 92.1% and 98%. The experimental gains are 1.76-2.08 dBi across the target operating frequency band, with near-omnidirectional radiation pattern. The simulation and experimental results are in good agreement. Moreover, the FNFC antenna achieves strong magnetic field distributions in $H_{\mathrm {x}}$ , $H_{\mathrm {y}}$ , and $H_{\mathrm {z}}$ orientations and holds promising potential for 3G/4G/LTE applications.

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