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Broadband Multi-Shaped Metasurface Circularly Polarized Antenna With Suppressed Non-CP Radiation Modes
(2023-01-01)
Supreeyatitikul, Nathapat
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Lertwiriyaprapa, Titipong
;
Chudpooti, Nonchanutt
;
Krairiksh, Monai
;
Phongcharoenpanich, Chuwong
In this research, a multi-shaped metasurface broadband circularly polarized (CP) patch antenna with parasitic elements is proposed for 5G new radio (NR) applications. The proposed metasurface CP patch antenna comprises triple-layered substrates without air gap. The upper layer sits with multi-shaped metasurface elements and parasitic patches. The middle layer consists of an L-shaped slot functioning as the ground plane, and the lower layer contains a microstrip and a fan-shaped stub functioning as the feed line. The proposed metasurface CP patch antenna with parasitic elements is evaluated using characteristic mode analysis (CMA). The CMA results indicate that the modal significance of Modes 1 and 2 of the multi-shaped metasurface CP antenna are orthogonal, giving rise to circular polarization. The non-CP radiation of Modes 3 and 4 are suppressed by using the multi-shaped metasurface elements and parasitic patches. The measured impedance bandwidth and axial ratio bandwidth are 42.85% (3.4 - 4.9 GHz) and 38% (3.27 - 4.6 GHz), achieving the maximum gain of 7.23 dBic at 3.7 GHz. The experiments demonstrate that the multi-shaped metasurface CP patch antenna with parasitic elements is suitable for 5G NR wireless applications. The novelty of this study is attributed to its utilization of multi-shaped metasurface elements and parasitic patches, which effectively suppress non-circularly polarized radiation modes.
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Compact Broadband Circularly Polarized Metasurface Antenna with Split-Annular Slot Ground Structure
(2023-01-01)
Supreeyatitikul, Nathapat
;
Chudpooti, Nonchanutt
;
Phongcharoenpanich, Chuwong
This paper presents a broadband CP MTS-inspired antenna with split-annular slot ground structure. The CP radiation and antenna configuration are deployed characteristic mode analysis (CMA). The proposed CP MTS-inspired antenna with split-annular slot ground structure comprised of upper substrate and lower substrate. The upper substrate consisted of 5× 5 uniformly MTS unit cells, and the split-annular slot ground plane and microstrip feed line are included on the lower substrate. In CMA results, the 5× 5 MTS-inspired unit cells generated CP radiation by Modes 1 and 2. Besides, the split-annular slot ground structure can be produced two orthogonal electric fields at the center frequency of 5 GHz by Modes 3 and 5 for excitation source. This proposed antenna achieved simulated IBW of 59.4% (3.57 - 6.55 GHz), and simulated ARBW of 24.22% (4.43 - 5.64 GHz). The maximum gain at 4.7 GHz is 5.72 dBic, which has RHCP characteristic radiation. The proposed antenna is appropriate functionally for C-band wireless applications.
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Non-Uniform Metasurface-Based Omnidirectional Patch Antenna Using Characteristic Mode Analysis
(2023-01-01)
Supreeyatitikul, Nathapat
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Chudpooti, Nonchanutt
;
Phongcharoenpanich, Chuwong
This paper proposes a non-uniform metasurface (MTS) omnidirectional patch antenna for WLAN applications. The antenna configuration is characterized by using characteristic mode analysis (CMA). The proposed non-uniform MTS-based patch antenna comprised a single-layer FR-4 substrate. Non-uniform square-shaped MTS unit cells were present in the upper-substrate layer. The lower-substrate layer is a circular-shaped ground plane. Besides, the excitation method of the proposed non-uniform MTS-based antenna is a single-probe-fed method. The use of a non-uniform square-shaped MTS structure achieved wide frequency resonance, resulting in wide impedance bandwidth. In addition, the circularly rotated direction of current distributions and magnetic fields on the non-uniform MTS structure can generate omnidirectional radiation by Mode 1 at 2.4 GHz (center frequency). The simulated IBW at 2.4 GHz is 26.67% (2.26 - 2.9 GHz). The optimum gain is 4.13 dBic at 2.8 GHz. The proposed antenna exhibits omni-directional radiation characteristics, making it well-suited for wireless communication applications.
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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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Wideband dielectric properties of silicon and glass substrates for terahertz integrated circuits and microsystems
(2021-05-01)
Chudpooti, Nonchanutt
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Duangrit, Nattapong
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Burnett, Andrew D.
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Freeman, Joshua R.
;
Gill, Thomas B.
This paper presents a comprehensive study of the optical and electrical dielectric material properties of six commonly-used silicon and glass substrates at terahertz (THz) frequencies, including refractive index, absorption coefficient, dielectric constant and loss factor. The material characterization techniques used in this paper feature THz time-domain transmission and reflection spectroscopy with the measurement frequencies from 0.5 THz up to a maximum of 6.5 THz. Of the six selected dielectric and semiconductor substrates, two are silicon wafers with resistivities ranging from 0.001 to 0.02 Ω-cm. From the measurement results, loss tangents of the selected silicon wafers range from 0.680 to 5.455 and the dielectric constants are from 1.079 to 17.735. The four other wafers are all glass-based substrates: D263 glass, Borofloat 33 glass, fused silica and Sapphire. From the measurements, it is found that the THz dielectric properties vary considerably between the substrate samples e.g. dielectric constants range from 1.925 to 3.207 while loss tangents are from 0.042 × 10-3 to 0.127. Most of the selected silicon and glass-based substrates are quite useful for many THz applications, e.g., THz integrated circuits (THz ICs), THz microsystem technologies (THz MSTs) and THz system-on-a-chip (THz SoC) and system-on-substrate (SiP).
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Synergistic effect of nickel nanoparticles and carbon nanotubes buckypaper for enhancement of microwave shielding properties
(2020-01-01)
Sukgorn, Nuttaya
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Yordsri, Visittapong
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Thanachayanon, Chanchana
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Horprathum, Mati
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Chudpooti, Nonchanutt
Carbon nanotubes (CNTs) are considered as the most promising materials to solve the electromagnetic interference (EMI) issue. Various forms of CNTs including CNTs/polymer composites, metal nanoparticles-decorated CNTs and freestanding CNT buckypapers (CNT BPs) have been proposed to enhance shielding effectiveness. In this study, the synergistic effect of nickel nanoparticles (NPs) and relatively short CNTs for the enhancement of microwave shielding properties was investigated. CNT BPs were prepared by vacuum filtration of well-dispersed multi-walled CNTs and subsequently nickel was decorated on the CNT BPs (Ni/CNT) by pulsed DC sputtering technique with different deposition times of 0, 5, 10 and 15 min (hereinafter referred to as CNi0, CNi05, CNi10 and CNi15, respectively). The diameter of Ni/CNT increased from 8.74±0.53 to 72.5±3.2 nm and the conductivity improved from 9.57±0.87 to 12.57±0.59 S/cm when the nickel deposition time was 15 min. Nickel NPs were the mixed phases of nickel and nickel oxide with a dominant nickel phase. The shielding effectiveness at the frequency of 9.5 GHz achieved to-34.1 dB for CNi15. The enhancement of shielding effectiveness of CNi15 is attributed to the synergistic effect of CNTs and nickel NPs on wave dissipation.
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Radio-frequency characterization of multi-walled carbon nanotube/poly-lactic acid composites
(2017-01-01)
Sukgorn, Nuttaya
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Siraleartmukul, Krisana
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Yordsri, Visittapong
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Chudpooti, Nonchanutt
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Chaimool, Sarawuth
Nowadays radio and microwave frequencies are widely used in wireless broadcastings and communications. But these waves can cause electromagnetic interferences in some electronic devices, including the equipment used in hospitals. The problems of the electromagnetic interference can be solved by using the materials that can reflect and/or absorb radio-frequency (RF) and microwaves. The shielding effectiveness (SE) of a material depends on its conductivity and the electrical permittivity. Recently, carbon nanotubes (CNTs) have been proposed as promising materials for shielding applications owing to its flexibility, durability, lightweight and exceptional electrical conductivity compared to conventional metal. In this work, the RF properties of multi-walled carbon nanotube (MWCNT) composites were investigated. Poly-lactic acid (PLA), a natural bio-degradable material, is used as the polymer matrix. The composites with different MWCNT concentrations (0 to 0.4 wt%) were prepared and molded into thin rectangular samples (5.6 cm x 6.3cm). The surfaces of the composites were morphologically characterized by a scanning electron microscope. The electrical permittivity of the samples was measured by using a vector network analyzer and a microstrip resonator within a range of 1-11 GHz. The effects of MWCNT concentration on electrical permittivity will be discussed.

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