研究者業績
基本情報
- 所属
- 千葉大学 フロンティア医工学センター 准教授
- 学位
- 博士(工学)(東京工業大学)Ph.D.(東京工業大学)
- J-GLOBAL ID
- 200901040108092262
- researchmap会員ID
- 1000169309
- 外部リンク
受賞
21-
2022年3月
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2021年9月
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2020年9月
論文
179-
Bulletin of Glaciological Research 42 19-37 2024年6月 査読有り
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IEICE Communications Express 13(6) 168-171 2024年6月 査読有り最終著者責任著者
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IEEE Open Journal of Antennas and Propagation 5(2) 340-535 2024年4月 査読有りMeander Line Antenna (MLA) is widely employed in compact electronic devices, such as cellular phones and WLAN terminals, owing to its electrically small size. To facilitate practical antenna design, essential equations encompassing self-resonant structure, input resistance, antenna efficiency, and Q factor have been systematically developed. However, the prior self-resonant equations included only inductive reactance (XC), neglecting the capacitive reactance (XD) equation. This manuscript addresses this gap by introducing new design equations, presenting a newly derived XD equation and an improved Q factor expression. The inadequacies of the existing Q factor equation, reliant on the radius of a sphere encompassing the antenna, are addressed by proposing a more fitting expression that incorporates antenna structural parameters using the ratio of reactance to resistance. The overview of existing design equations sets the stage for the introduction of these newly developed equations. To assess the accuracy of electromagnetic (EM) simulation results, a comparative analysis is conducted between simulated and theoretically calculated input resistance values. The derivation of new reactance equations involves the development of XC equations based on electromagnetic theory. The XD equation is established by deriving the stored charge equation from electrical near-field distributions obtained through EM simulations. By applying the relationship between charge and capacitance, a new XD equation is obtained. Subsequently, a new self-resonant equation is derived, and the validity of the newly derived equations is confirmed through EM simulation results, ensuring their accuracy. Two MLA prototypes, with lengths of 0.05 and 0.1 wavelengths at 405 MHz, are fabricated and experimentally validated. Smith chart measurements confirm the self-resonant condition and input resistance. By correlating with the VSWR characteristics, the obtained Q factor of approximately 100 aligns successfully with the results from the reactance equation. The antenna gain is verified at -7.7 dBi and -3.5 dBi for antennas with lengths of 0.05 and 0.1 wavelengths, respectively. These findings establish the practical applicability of the proposed equations for antenna design and elucidate the performance of practical antennas.
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e28061-e28061 2024年3月 査読有り最終著者
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IEICE Transactions on Communications E107-B(1) 206-213 2024年1月1日 査読有り最終著者責任著者
MISC
613-
2024年8月 査読有り招待有り筆頭著者責任著者
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IEEE AP-S/URSI 2024 2347-2348 2024年7月 査読有り最終著者責任著者
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2024 18th European Conference on Antennas and Propagation (EuCAP2024) 2024年3月 査読有り
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2023 International Conference on Emerging Technologies for Communications (ICETC2023) 2023年12月 査読有り
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年11月 査読有り最終著者Applications of radio waves for underwater communication are currently growing. Utilization of the lateral wave is considered promising. In this paper, electromagnetic simulation data are obtained in different seadepth at 100 MHz. Normal-mode helical antenna is employed for transmit antennas. The seadepth are changed from the seasurface to 50 cm depth. Visual 2D electric field distributions of the seasurface antenna indicate the lateral wave propagation situation. At 20 cm and 50 cm depth, the propagation attenuation becomes the same as the theoretical value based on the sea conductivity.
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年11月 査読有りTo realize a comprehensive community care system in a super-aging society, regular acquisition of medical imaging information is desirable in the community and home environment for preventive and preliminary diagnosis. MRI is suitable in community medicine because of the high soft tissue contrast and no exposure to radiation. MRI using permanent magnet arrays (PMA) has recently been considered an appropriate modality. PMA has a nonlinear magnetic field gradient, and its static field strength is weaker than conventional MRI. Therefore, the RF coil used in PMA-based MRI must have broadband characteristics and low resistance. In this study, we adopted a cylindrical structure for the RF coil, and the optimal combination of parameters was obtained by analyzing several models with different shapes. We fabricated and measured RF coils using these parameters and investigated fabrication feasibility and error factors.
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年11月 査読有りThis paper presents the simulation results and evaluates the performance of the meander line antenna (MLA) in human body conditions, comparing different permittivity and conductivity values, including muscle, and fat tissues. The electrical characteristics obtained by simulation, such as input resistance (Rin), and MLA self-resonant structure are discussed. The theoretical and simulation results are compared for the validation of the simulation environment. The absorption loss is calculated and compared with the simulation results. The input resistance increases when the antenna conductivity increases.
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年11月 査読有りIn recent years, the smartphone structure has become more complicated owing to functionality improvements and miniaturization. To evaluate human exposure to electromagnetic waves, we have modeled and simulated smartphones in detail. In an era where various smartphones are being developed, simplification of smartphone models is necessary to evaluate them quickly. It takes time to model the antenna of smartphone terminals. Therefore, we propose a method for constructing a simple smartphone model that generates the same distribution as that of a real terminal using the specific absorption rate, which is an index for evaluating electromagnetic wave exposure, and confirm its validity.
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年11月 査読有り最終著者責任著者Bedsores are localized injuries to the skin and subcutaneous tissue caused by prolonged pressure on the skin and decreased blood flow. Early treatment of bedsores can shorten the treatment period. In our research, an antenna is placed between a bed and a mattress, with the aim to detect bedsores in the early stage by non-contact microwave detection. In this paper, we reproduced bedsores in the sacral region of a numerical human model (Taro) provided by the NICT (National Institute of Information and Communications Technology), and detected the bedsores using a patch antenna in the 10.525 GHz band. As a result, it was confirmed that the bedsores could be detected even in the numerical human model. In the future, we plan to develop a method for detecting early stage bedsores such as Stage I, develop a phantom that simulates the numerical human model, and conduct measurement experiments to evaluate the validity of the simulation.
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年11月 査読有り最終著者In hyperthermia therapy, it is necessary to ensure electromagnetic radiation is concentrated only on the targeted area and not in the surrounding healthy tissues. An initial focused dielectric lens operated at 2.45 GHz has been designed to achieve a small focusing spot in 2/3 muscle equivalent phantom. The thickness of the initial lens is then minimized to develop a thin lens. The spot size and power density at the focusing spot are evaluated between the thin lens and the initial lens design. Power density achieved by the thin lens is in good agreement to that of the initial lens. The treatment spot of 2.78 cm is capable of being achieved by the thin lens. The proposed thin lens design might be suitable for achieving small focusing spot on human body.
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年11月 査読有りThe meander line antennas (MLAs) are used for small-sized antennas in the self-resonant condition where capacitive reactance (XD) and inductive (XC) reactance are equal. In the previous study, XD and XC are not explicitly shown in the structural equation of self-resonance. In this paper, XC, and XD are derived from the self-inductance of the crank part and the stored charge at the edge area of the MLA. By equalizing XD and XC, the self-resonant equation is obtained. The self-resonant structures by the equation and results of electromagnetic simulations agree very well. The usefulness of the equation is ensured.
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The 2023 International Symposium on Antennas and Propagation (ISAP2023) 2023年10月 査読有り招待有り筆頭著者責任著者We consider using electromagnetic waves in seawater suitable for use in shallow water areas because the loss due to seawater is significant, and communication is faster than acoustic waves, although at short distances. Then, we are investigating an underwater position estimation system using electromagnetic waves. The location of divers and AUVs is essential in a broader range of scenarios. This paper presents the underwater position estimation principle and actual estimation results to show the technique's effectiveness.
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2023 International Conference on Electromagnetics in Advanced Applications, ICEAA 2023 235-236 2023年10月 査読有り最終著者責任著者Bedsores are injuries caused by pressure on the skin for a long time and obstruction of blood flow. As the damage progresses, the treatment period becomes longer. In some cases, patients require surgery. So early detection is essential. In this study, we develop a noncontact bedsores detection system using electromagnetic waves at 10.5 GHz.In this report, we investigated the detectable range in bedsores detection.
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2023 International Conference on Electromagnetics in Advanced Applications, ICEAA 2023 192-193 2023年10月 査読有り最終著者責任著者When divers rescue people who have accidents at sea, they are in a hazardous environment. If they can confirm their positions, their activities will be conducted more safely and reliably. In this research, we propose an undersea positioning technology using electromagnetic waves with low frequencies. In this report, we consider position estimation using the loop antenna in the sea using a pseudo-scale model.
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2023 International Conference on Electromagnetics in Advanced Applications, ICEAA 2023 45-46 2023年10月 査読有り最終著者責任著者In recent years, sensors have been installed every-where in our daily lives to monitor human flow due to COVID-19 pandemic and for inventory control in warehouses.It is impractical to supply power and information to these IoT devices and sensors individually, and the use of microwave-based WIPT (Wireless Information and Power Transmission) for data and power transmission to each sensor is being considered. However, long-distance transmission is difficult due to the large free-space loss in the current microwave-based WIPT.In this research, we investigate a system and a device of a repeater to improve the transmission efficiency and extend the transmission distance of the WIPT system. In this paper, we report on the design and fabrication of a circuit for storing reliable power at low input power.
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9th IEEE International RF and Microwave Conference (RFM 2022) 117-120 2022年12月 査読有り最終著者
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9th IEEE International RF and Microwave Conference (RFM 2022) 8-11 2022年12月 査読有り招待有り
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2022 International Symposium on Antennas and Propagation (ISAP) 2022年10月31日 査読有り最終著者責任著者
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2022 International Symposium on Antennas and Propagation (ISAP) 2022年10月31日 査読有り
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2022 International Symposium on Antennas and Propagation (ISAP) 2022年10月31日 査読有り最終著者責任著者
書籍等出版物
11-
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Wiley-IEEE Press 2014年8月25日 (ISBN: 9781118388617, 1118388615) -
講演・口頭発表等
113-
電子情報通信学会総合大会講演論文集 2013年3月5日 一般社団法人電子情報通信学会
Works(作品等)
12共同研究・競争的資金等の研究課題
19-
日本学術振興会 科学研究費助成事業 2023年4月 - 2026年3月
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日本学術振興会 科学研究費助成事業 2023年4月 - 2026年3月
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日本学術振興会 科学研究費助成事業 2022年4月 - 2025年3月
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日本学術振興会 科学研究費助成事業 2022年4月 - 2025年3月
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2022年4月 - 2025年3月