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Numerical analysis of heat transfer and tissue deformation in liver cancer during microwave ablation: A comparison of bioheat and porous media models
(2025-08-01)
Preechaphonkul, Wutipong
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Mongkol, Vannakorn
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Sakonkanapong, Arnon
;
Rattanadecho, Phadungsak
This study presents a numerical comparison of microwave ablation using the Pennes bioheat and porous media models in a deformed liver cancer geometry. A single slot coaxial antenna operating at 2.45 GHz with a power of 10 W for 10 min was simulated using the finite element method, incorporating electromagnetic wave propagation, heat transfer, and tissue deformation. Validation against published experimental data and a mesh independence test confirmed the accuracy of the model. Results indicate up to a 6.7 % higher specific absorption rate in the porous media approach, contributing to a temperature difference of approximately 10–13 % at 10 min compared to the Pennes model. Peak von Mises stress increased by more than 2 Pa in tumor regions, and necrosis progression differed between the models. While both models predicted complete tumor cell death, the Pennes bioheat approach consistently reached thresholds sooner in both tumor and adjacent healthy tissue. These findings highlight the role of tissue porosity and convection in heat transport and deformation, demonstrating the porous media model's improved predictive capability for longer ablation durations and its potential for optimizing treatment protocols.
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Elliptical ring antenna excited by circular disc monopole for UWB communications
(2020-01-01)
Nakprasit, Krittaya
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Sakonkanapong, Arnon
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Phongcharoenpanich, Chuwong
This research proposes a compact elliptical ring antenna excited by a circular disc monopole (CDM) for ultra-wideband (UWB) communications. In the study, time- and frequency-domain pulse distortions of the antenna in the transmission mode were characterized by magnitude and phase of the antenna transfer function (H<inf>rad</inf>). The results showed that the gain and magnitude of H<inf>rad</inf> in the boresight direction are sufficiently flat with linear phase response. The average antenna gain is 3.9 dBi over the UWB spectrum. The antenna also exhibits low pulse distortion with the correlation factors (ρ) of 0.98 and 0.93 for the fifth-order derivative Gaussian pulse and modulated Gaussian pulse with 6 GHz band rejection. The CDM-excited elliptical ring antenna possesses several attractive features, including wide bandwidth, flat gain, compactness, low cost, and low distortion.
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Near-Field HF-RFID and CMA-Based Circularly Polarized Far-Field UHF-RFID Integrated Tag Antenna
(2020-01-01)
Sakonkanapong, Arnon
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Phongcharoenpanich, Chuwong
This research proposes an integrated high-frequency (HF) and ultrahigh-frequency (UHF) passive radio frequency identification (RFID) tag antenna for near-field (13.56 MHz) and far-field (920-925 MHz) communication. This tag antenna is advantageous for the applications with lossy material in the near-field communication and mitigates polarization loss in the far-field communications. The HF-RFID tag antenna is of square spiral structure, and the circularly polarized UHF-RFID structure consists of a square loop radiator with cascading loop feeding and shorted stub. The structure of HF-RFID tag antenna situated inside the circularly polarized UHF-RFID tag can avoid the significant effect of the near-field magnetic coupling from the square loop. The UHF-RFID tag antenna is realized by using characteristic mode analysis for wideband circular polarization. The HF-RFID structure is conjugate-matched with NXP NT3H2111 chip, and the UHF-RFID structure is conjugate-matched with NXP G2X chip. Simulations were carried out, and an antenna prototype was fabricated. The experimental results reveal that the radiation pattern of UHF-RFID tag antenna is bidirectional with a gain of 0.31 dBic. The impedance bandwidth covers the frequency range of 903-944 MHz, and the axial ratio in boresight direction at 922.5 MHz is 1.67 dB, with the axial ratio bandwidth over 863-938 MHz. The maximum near-field and far-field reading ranges are 4.9 cm and 8.7 m. The proposed integrated dual-band passive tag antenna is operationally ideal for HF-RFID and UHF-RFID applications.
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Broadband circularly polarized microstrip patch antenna using circular artificial ground structure and meandering probe
(2020-01-01)
Pookkapund, Khanet
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Sakonkanapong, Arnon
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Kuse, Ryuji
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Phongcharoenpanich, Chuwong
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Fukusako, Takeshi
To enhance axial ratio (AR) bandwidth, this research proposes a circularly polarized (CP) single-fed microstrip patch antenna using a circular artificial ground structure (AGS) and meandering probe. To achieve broader AR bandwidth, the circular AGS is populated with rectangular unit cells and partially cut unit cells along the circular contour, while the meandering probe is used to improve the impedance bandwidth. Simulations are performed and results compared with that of conventional rectangular-AGS antenna. The simulation results show that the circular-AGS antenna, given 62 mm circular ground plane, achieves broader impedance (5.12 - 9.00 GHz and 54%), AR (5.21 - 8.27 GHz and 45%) and gain bandwidths (3.85 - 7.00 GHz and 58.06%), in comparison with the rectangular-AGS antenna (4.50 - 7.45 GHz and 49%; 4.52 - 7.42 GHz and 21%; and 4.00 - 6.80 GHz and 51.58% for impedance, AR and gain bandwidths). The circular-AGS antenna is capable of converting linear polarization in the off-axial ratio band into circular polarization. To verify, a circular-AGS antenna prototype is fabricated and experiments undertaken. The experimental impedance, AR and gain bandwidths of the circular-AGS antenna are 47.82% (5.17 - 8.42 GHz), 43.81% (5.24 - 8.17 GHz) and 60.74% (3.75 - 7.00 GHz). The proposed circular-AGS antenna can achieve broader AR bandwidth and is thus ideal for broadband CP applications. The novelty of this research lies in the use of circular AGS to effectively enhance AR bandwidth, as opposed to rectangular AGS which is conventionally used in CP polarizers.
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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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Multi-parents genetic algorithm optimization scheme for linear array antenna synthesis
(2017-04-26)
Sakonkanapong, Arnon
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Todnatee, Sarayoot
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Phongcharoenpanich, Chuwong
This research has proposed the improved iterative generic algorithm (GA) optimization scheme by using multi-parents crossover and adaptation mutation to synthesize the radiation pattern of an aperiodic (nonuniform) linear array antenna. The aim of the iterative optimization is to achieve a radiation pattern with a side lobe level (SLL) less than or equal to -20dB. In the optimization, the proposed scheme iteratively optimizes the array range (spacing) and the number of array elements, whereby the array element with the lowest absolute complex weight coefficient is first removed and then the second lowest and so on. The removal (the element reduction) is terminated once the SLL is greater than -20dB and the elemental increment mechanism is triggered. The results indicate that the proposed iterative GA optimization scheme is applicable to the non-uniform linear array antenna and also is capable of synthesizing the radiation pattern with SLL less than or equal to -20dB.

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