Tuntrakool, Sunti

Preferred name

Tuntrakool, Sunti

Alternative Name

Tuntrakool, S.

Main Affiliation

School of Industrial Education and Technology

sunti.tu@kmitl.ac.th

Now showing 1 - 10 of 11

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Polarization insensitive switchable metamaterial absorber/reflector for x-band applications
(2020-01-01)
Mustapha, M. G.
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Rahim, M. K.A.
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Murad, N. A.
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Ayop, O.
;
Tuntrakool, S.
A unit cell of squared shaped polarization-insensitive switchable metamaterial absorber/reflector is presented. The structure operates at 10.20 GHz under both absorber mode and reflector mode configurations. Copper wire bridging the gaps to form a circular shape structure were used as switches for operation mode selections. The structure was designed on an FR4 substrate, and the incidental wave angles were varied from 0 to 50 degrees. The structure demonstrated almost 100% absorption at resonance, 3.314 GHz percentage bandwidth at 80% as an absorber. On the other hand, as reflector, it demonstrated almost a 90% reflection and a usable bandwidth of 3.327 GHz.
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UWB MIMO antenna design and analysis at millimetre wave frequencies
(2025-01-01)
Mohamad Nazer, Mohamad Aiman Hadi
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Rahim, Mohamad Kamal A.
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Murad, Noor Asniza
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Samsuri, Noor Asmawati
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Pramudita, Aloysius Adya
The Ultra-Wideband (UWB) antenna is widely used in radar systems due to its wide bandwidth and high diversity gain. However, UWB systems also experience challenges related to multipath fading. To address these issues, multiple-input-multiple-output (MIMO) technology has been introduced. To improve the performance of MIMO systems, it is essential for the elements within the MIMO antenna array to exhibit low correlation and high total efficiency. In this paper a design and simulation of a printed UWB antenna with additional MIMO implementation. The simulation results from three different MIMO configurations were systematically compared to assess their performance based on three parameters of MIMO: the Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Mean Effective Gain (MEG). In this proposal of the project, the evaluation of results is primarily cantered around the design of UWB antenna and analysis of the MIMO configurations.
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Broadband Reflective Metasurface at X-band Frequency Using Snowflakes Fractal Ring Design
(2025-01-01)
Yaziz, Nur Syahirah Mohd
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Rahim, Mohamad Kamal A.
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Samsuri, Noor Asmawati
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Zubir, Farid
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Tuntrakool, Sunti
A broadband reflective metasurface has been designed to integrate inward and outward fractal Koch rings operating at X-band frequencies. The integration between the inward and outward fractal Koch ring creates the snowflake fractal shape that operates at a center frequency of 10 GHz. Based on the simulated results, the reflection values are 0.9 with the reflection phase of 1800 which is between 900 to -900. Overall, all resonance frequencies exhibit more than 90% reflected power, with bandwidth of 1.90 GHz that cover from 8.70 GHz to 10.60 GHz.
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Dual-Band Reflective Metasurfaces for 5G mmWave Applications: Design, Analysis, and Waveguide Validations
(2026-01-01)
Mohammed, Sunusi Garba
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Samsuri, Noor Asmawati Binti
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Rahim, Mohamad Kamal B.A.
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Ripin, Nabilah Binti
;
Taufiqqurrachman
This paper presents a dual-band reflective metasurface unit cell for millimeter-wave RIS applications operating at 26 GHz and 28 GHz, covering the 5G n258 and n257 bands. The proposed design features a hybrid resonator structure to achieve a consistent phase trend and strong reflection performance across the 5G mmWave frequency band. To ensure stable dual-band performance of the unit cell, parametric optimization is conducted. The unit cell is investigated through Floquet simulations and WR-34 rectangular -to-square waveguide-transition-based full-wave simulations, followed by experimental validation using a fabricated WR-34 rectangular-to-square waveguide transition. The simulated resonances at 26 GHz and 28 GHz are experimentally observed at 26.7 GHz and 28.9 GHz, respectively, indicating minor frequency deviations. Measured results demonstrate reflection magnitudes of -1.80 dB at 26.7 GHz and -0.80 dB at 28.9 GHz, with corresponding phase responses of - 68° and -13°, and bandwidths of 5.12% and 6.07%, respectively.
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Geometry-Driven Performance of Unit Cells in Multiband Reflective Metasurfaces: A Comparative Study
(2025-01-01)
Taufiqqurrachman
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Rahim, Mohamad Kamal B.A.
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Samsuri, Noor Asmawati Binti
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Wijayanto, Yusuf Nur
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Yaziz, Nur Syahirah Mohd
A multiband reflective metasurface can be designed using a multi-ring resonator, where the resonator can take various shapes such as circular, square, hexagonal, triangular, and others. This paper presents a comparative study of unit-cell multiband reflective metasurfaces based on their geometric structure, focusing on reflection magnitude, reflection phase, and bandwidth performance of hexagonal and triangular shapes. Both proposed designs are designed and simulated at X-band frequencies using an F4BMX220 substrate with a thickness of 1.5 mm. Simulation results show that the hexagonal shape offers better reflection performance and a wider bandwidth compared to the triangular shape.
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Integer- And fractional-order VCO using non-inertial amplitude stabilization and modern active elements
(2020-04-28)
Sotner, Roman
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Petrzela, Jiri
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Jerabek, Jan
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Langhammer, Lukas
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Polak, Josef
This paper introduces design of the linearly tunable quadrature voltage-controlled oscillator (VCO) using modern off-the-shelf active elements suitable for the design of electronically adjustable applications. The simplified topology was achieved using non-inertial stabilization of amplitude. It allows targeting adjustability of the oscillation frequency only into lossless integrator part of the topology. This arrangement simplifies the design and the tenability also. Derived symbolical expressions indicate that gain adjustment of used amplifiers (that are still in single path) does not influence amplitude and phase shift ratio of generated waveforms, which is a beneficial feature. The performances of the circuit are tested experimentally in band of units of MHz and results confirmed expected behavior. Initial study of the oscillator with fractional-order capacitors is presented and discussed. Results are supported by laboratory measurements.
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Multiband Reflective Metasurface at X-Band Frequency Using Multi-Square Ring Resonators (SRRs)
(2025-01-01)
Taufiqqurrachman
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Rahim, Mohamad Kamal B.A.
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Asmawati Binti Samsuri, Noor
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Wijayanto, Yusuf Nur
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Syahirah Mohd Yaziz, Nur
A multiband reflective metasurface has been designed using a multi-Square Ring Resonator (SRR) operating at X-band frequencies. Each SRR is designed to resonate at 8, 10, and 12 GHz, respectively. Based on the simulated results, the reflection values are -0.4 dB at 8 GHz, -1.86 dB at 10 GHz, and -1.99 dB at 12 GHz, while the reflection phases are -1.06° at 8 GHz, -9.8° at 10 GHz, and -1.98° at 12 GHz. Overall, all resonance frequencies exhibit more than 60% reflected power, with bandwidths of 0.67 GHz at 8 GHz and 0.2 GHz at 10 and 12 GHz.
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Comparison between Snowflake Fractal and Koch Fractal for Intelligent Reflecting Surface
(2025-01-01)
Yaziz, Nur Syahirah Mohd
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Rahim, Mohamad Kamal A.
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Samsuri, Noor Asmawati
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Zubir, Farid
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Tuntrakool, Sunti
This paper compares two fractal metasurface designs for Intelligent Reflecting Surfaces at X-band which is with a snowflake-shaped fractal ring and a fractal Koch metasurface. The snowflake ring design with a 10GHz center frequency achieves very high reflectance (~90%) at resonance and a bandwidth of about 1.90 GHz. The Koch-fractal design response with a bandwidth of 2.10 GHz at a center frequency of 10GHz. The method for both fractal metasurfaces and a comparable on their reflection coefficients, phase behaviour, bandwidth and current distributions are discussed in section II and section III.
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AWC 708C Laser Cutting Manual Learning Set
(2020-09-23)
Sae-Jeng, Wasin
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Tuntrakool, Sunti
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Maunsaiyat, Somchai
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Supavarasuwat, Piya
This research paper presents AWC 708C laser cutting manual learning set. It is a learning set which is relevant to high school courses and taught in a module (namely 30291 Creativity and Innovation). The researchers have developed a combination between the augmented reality technology and the AWC708C laser cutting learning kit to make them more attractive and reduce danger to users by adding additional security systems to the device. Also, it includes teaching how to use the machine through a designed worksheet to accompany with an augmented reality technology which is intended to be suitable for high school students in grade 10 (Mathayomsuksa 4). The results of this research found that overall quality of the AWC 708C laser cutting learning kit is in good quality level with average of 4.48±0.58. Outstanding results from an overall quality assessment are the convenience in preparing the equipment and the simple method of using the machine. Also, the quality level of the worksheet is in good quality level with average of 4.24±0.66. In addition, it was found that the results of the evaluation on satisfaction with the AWC 708C laser cutting machine learning kit is in very good level with average of 4.77±0.42. From the comparison of academic achievement between before and after using the learning set analyzed by t-test, it is found that the pre and post test scores of the sample groups had an average score of 5.50 and 8.96, respectively. From t distribution table which has df = 23, confidence value at 0.05 level with t = 2.707, the analysis result is 15.37 higher than the t distribution table. It is implied that the results of the pre-test achievement were different from the post-test achievement scores with significance level of 0.05. From the research hypothesis, it is found that those who studied with AWC708C laser cutting manual learning set had academic achievement after studied higher than before, according to the assumptions. Hence, in this research it can be concluded that the quality of the AWC 708C laser cutting machine learning kit can be increased.
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Characterization of the koch fractal embedded hexagonal loop frequency selective surface structure for X-band application
(2020-11-01)
Mohamed Nafis, Nur Biha
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Rahim, Mohamad Kamal A.
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Ayop, Osman
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Majid, Huda A.
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Tuntrakool, Sunti
This paper presented the bandstop Koch fractal embedded hexagonal loop frequency selective surface (FSS) for the X-band application. The simulated transmission coefficient response () had been obtained by using CST software. The surface current distribution and the electric field density are illustrated to explain in detail the of the fractal based FSS structure. The proposed structure is highly insensitive towards angular stability and also polarization independent up to . The parametric analysis on the effect of the periodicity, width, and height of the fractal FSS structure on the has been illustrated and discussed thoroughly.

Tuntrakool, Sunti

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