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Investigation of 3-D Printed, Electrically Small, and Thin Magnetic Dipole Antenna
Kong, Myeongjun,Lee, Su-Hyeon,Shin, Geonyeong,Nah, Junghyo,Yoon, Ick-Jae IEEE 2018 IEEE antennas and wireless propagation letters Vol.17 No.4
<P>A novel design of electrically small, extremely thin, and horizontally polarized magnetic dipole antenna is proposed. It is composed of multiple folded arms packed in an extremely thin height of 0.0016λ, with the electrical size <I>ka</I> of 0.276. The radiation efficiency is 87% from the simulation. The radiation properties are investigated, and its operation as a small magnetic dipole antenna is confirmed. A three-dimensional printing technology is used for building the prototype due to the complexity of the proposed structure. The experimental results show good agreement with the computed expectation values.</P>
Investigation of 3D Printed Electrically Small Folded Spherical Meander Wire Antenna
Myeongjun Kong,Geonyeong Shin,Su-Hyeon Lee,Ick-Jae Yoon 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.4
The radiation properties and fabrication precautions of a 3D printed, electrically small folded spherical meander wire monopole antenna are investigated. The antenna is self-resonant and shows sufficiently high radiation efficiency at an electrical size ka of 0.4, with the radiation quality factor Q approaching the lower physical bound. In antenna fabrication, the possible structural deformation due to gravity is examined before the antenna frame is 3D-printed. The required conductivity is achieved by multiple manual paintings of a silver paste. The radiation efficiency and pattern show very good agreement with the computed expectations, whereas the resonant frequency deviates by 11.8%. The method to minimize such a fabrication error when using 3D printing technology for wire antennas is discussed.
아크 융해로를 이용한 β-Ti<SUB>3</SUB>O<SUB>5</SUB> 및 λ-AlxTi<SUB>3-x</SUB>O<SUB>5</SUB>의 합성
공민식(Minsik Kong),김서희(Seohee Kim),김민재(Min Jae Kim),강명준(Myeongjun Kang),지광철(Gwangcheol Ji),박성욱(Seonguk Park),이지성(Jisung Lee),손영준(Yeongjun Son),박성균(Sungkyun Park),옥종목(Jong Mok Ok) 한국물리학회 2024 새물리 Vol.74 No.1
마그넬리(Magneli)상 티타늄 산화물인 Ti₃O<SUB>5</SUB>는 514 K에서 β상에서 λ상으로 변화하며 절연체에서 도체로 변화하는 금속-절연체 전이(metal-insulator transition; MIT)를 보인다. Ti<SUB>5</SUB>O<SUB>5</SUB>의 MIT는 큰 저항 변화와 높은 열에너지 저장 특성을 동반하는 것으로 알려져있어 높은 응용성을 가지고 있다. 이러한 Ti₃O<SUB>5</SUB>의 전기적 혹은 열적 특성을 활용하기 위해선 균일한 시료의 합성과 상전이 온도의 제어가 우선되어야 한다. 본 연구에서는 아크 융해로(arc melting furnace)를 이용한 티타늄 환원법으로 Ti₃O<SUB>5</SUB>를 합성하였고, 그 구조를 탄소 환원법으로 제조한 Ti₃O<SUB>5</SUB>와 비교하였다. 또한, 티타늄 환원법을 이용해 Al이 도핑된 AlxTi₃−xO<SUB>5</SUB>를 합성하고 Al 도핑 비율에 따른 구조, 상전이 온도 및 잠열량을 확인함을 통해 아크 융해법이 Ti₃O<SUB>5</SUB>를 합성하고 상전이를 온도를 제어하는데 효과적인 합성법임을 확인하였다. Ti₃O<SUB>5</SUB> exhibits a metal-insulator transition (MIT) accompanied by a structural change from β- phase to λ-phase at 514 K. During the transition, Ti₃O<SUB>5</SUB> demonstrates significant resistance changes and high thermal energy storage characteristics. To harness the beneficial characteristics of Ti₃O<SUB>5</SUB>, it is essential to develop a growth method that yields homogeneous samples and to control the phase transition temperature. In this study, we successfully synthesized high-quality β-Ti₃O<SUB>5</SUB> and λ-AlxTi₃−xO5 polycrystalline samples using an arc melting method. Furthermore, the structural and physical properties of β-Ti₃O<SUB>5</SUB> and λ-AlxTi₃−xO<SUB>5</SUB> were investigated as a function of the Al doping ratio. Our results suggest that the arc melting method provides an effective way to synthesize high-quality Ti₃O<SUB>5</SUB> and control the transition temperature of the MIT.
전기적 소형 Folded Slot Spherical Helix 자기 다이폴 안테나에 관한 연
신건영(Geonyeong Shin),공명준(Myeongjun Kong),이수현(Su-Hyeon Lee),윤익재(Ick-Jae Yoon) 한국전자파학회 2017 한국전자파학회논문지 Vol.28 No.4
본 논문에서는 FSSH(Folded Slot Spherical Helix) 자기 다이폴 안테나에 관한 추가적인 연구를 통해 안테나 시작품 제작에 용이성을 갖는 구조를 제안하고, 그 방사 특성을 분석하였다. FSSH 자기 다이폴 안테나의 folded element 개수와 그 사이 간의 거리 및 금속면의 두께를 조절하여 전기적 소형 크기에서 높은 효율을 유지하면서 상대적으로 간소화된 안테나 구조를 제안하였다. 시뮬레이션을 통해 제안된 안테나의 넓은 고효율 대역폭 특성을 non-Foster 정합회로를 통해 실질적으로 사용할 수 있음을 확인하였다. SLS(Selective Laser Sintering) 3D 프린팅 기술을 통해 안테나 시작품을 제작 및 측정하였다. 측정값은 구리 테이프 경계면의 높은 저항 손실로 인해 시뮬레이션에 비해 낮은 Q값 특성을 보인다. In this paper, we propose an FSSH(Folded Slot Spherical Helix) magnetic dipole antenna with a form factor easy to build and study its radiation properties. The number of folded arms, the gap between them and the metal thickness are tuned to achieve relatively simple structure to realize whereas maintaining high radiation efficiency at an electrically small size. The proposed design shows wide radiation efficiency bandwidth and it is confirmed by circuit simulation that the non-Foster impedance matching techniques could be utilized for its practical use. The prototype of the proposed antenna is built with the aid of an SLS(Selective Laser Sintering) 3D printing technology. The measured result shows lower Q impedance characteristic due to high resistive loss of the copper tape joints.