• Title/Summary/Keyword: $YBa_2Cu_3O_x film

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Fabrication of Novel Dual Mode Resonator Using Superconducting Thin Film Grown by Pulsed Laser Deposition (펄스 레이저 증착법에 의한 YBCO 박막증착과 이중모드 공진기의 제작)

  • Park, Joo-Hyung;Lee, Sang-Yeol;Ahn, Dal
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1546-1548
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    • 1998
  • Dual mode ring resonators(DMRR) have been fabricated using laser ablated $YBa_2Cu_3O_{7-x}$ superconducting thin films. The transition temperature of YBCO thin films were 85 - 88 K and the film thicknesses were about 5,000 $\AA$. Dual mode ring resonators were patterned by standard photolithography process and wet-etching. Then two-layer metal thin films (Ti/Ag) have been deposited for the ground plane on the back side of substrate by e-beam and thermal evaporation. The input/output feedline angles of each resonator were $60^{\circ}$, $100^{\circ}$, $180^{\circ}$. A network analyzer was used for testing the performance of the resonators in the frequency range of 6-13 GHz at 77 K.

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HTS Broadband-Array Antenna for Satellite Communication

  • 정동철
    • Progress in Superconductivity
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    • v.3 no.2
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    • pp.178-182
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    • 2002
  • Superconducting four-element patch array antenna was designed and fabricated using $high-T_{c}$ superconducting (HTS) thin film. The array antenna has single-feed circularly polarization and a resonance frequency of 11.85 GHz fur satellite communication system. To fabricate this antenna $YBa_2$$Cu_3$$O_{7-x}$(YBCO) superconducting thin films were deposited using rf-magnetron sputtering technique. Sequential rotation technique based on radiation elements($0^{\circ}$ , $90^{\circ}$, 1$80^{\circ}$, $270^{\circ}$ phase delay) was utilized to achieve circularly polarization. Simulated and measured results, the analysis on resonant frequency(fr), return loss, and bandwidth are presented. The results show that 10 dB return loss bandwidth of the array antenna is 11.04 GHz~12.59 GHz (13.15%) and 3dB axial ratio bandwidth is 11.42~12.52 GHz (9.2%).).).

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Fabrication and Characterization of Miniaturized HTS Microstrip Antennas Using "H"-type Resonator (H 형태 공진기를 이용한 소형화된 HTS 안테나의 제작 및 특성 해석)

  • 정동철;윤창훈;황종선;최창주
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.7
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    • pp.282-287
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    • 2003
  • ″H″ type resonator has the advantage for the miniaturization of high-T7 superconducting (HTS) microstrip antenna in comparison with the conventional microstrip antenna such as rectangular type or circular type. In this paper we designed miniaturized HTS antennas using this "H"-type resonator and reported the characteristics of our antennas including return loss, bandwidth, radiation patterns, efficiency and so on. To fabricate the "H" type antenna, HTS YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) thin films were deposited on MgO substrates using rf-magnetron sputtering. For comparison between normal conducting antennas and superconducting antennas, the gold antennas with the same dimension were also fabricated. An aperture coupling was used for impedance matching between 50 $\Omega$ feed line and HTS radiating patch. The ″H" type superconducting antenna showed the performance of 1.38 in SWR, 26 % in efficiency, and 13.8 dB in the return loss superior to the normal conducting counterpart.

Development of Small-sized SQUID and Direct-coupled Electronics for High-$T_c$ Scanning SQUID Microscope (소형 SQUID, 직접 되먹임 방식 전자회로, 고온초전도 SQUID 주사현미경의 개량)

  • Baek, B.;Lee, S. M;Yun, J. H.;Khim, Z. G.
    • Progress in Superconductivity
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    • v.3 no.1
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    • pp.78-82
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    • 2001
  • The spatial resolution of $high-T_{c}$ scanning SQUID microscope is limited by the washer size of SQUID and the gap distance between SQUID sensor and the sample. In this work, we tried to improve the spatial resolution of scanning SQUID microscope by reducing the size of SQUID sensor fabricated with $YBa_2$$Cu_3$$O_{7}$ thin film. Outer dimensions of the SQUiDs we tested are 24 $\mu\textrm{m}$ $\times$ $ 28\mu\textrm{m}$, $12 \mu\textrm{m}$ $\times$ $16\mu\textrm{m}$, $12\mu\textrm{m}$ x $12\mu\textrm{m}$, $10 \mu\textrm{m}$ $\times$ $10 \mu\textrm{m}$ each. To operate them in the flux-locked loop scheme, we used a direct-coupled electronics instead of using conventional electronics involving a modulation scheme. Since the direct-coupled feedback scheme does not require modulation current adjustment that poses as a practical difficulty in the SQUID operation in modulation-scheme, the direct feedback operation is rather simpler than the conventional modulation method. The resulting noise features were dominated by the noise of preamp in FLL electronics except that of the largest SQUID. The noise levels of SQUIDs are expected below 1$\times$$10^{-5}$ $\Phi_{0}$H $z^{1}$2/ (at 300 Hz), that is a typical noise level for SQUID made of $YBa_2$C $u_3$$O_{7}$ thin film. The data acquisition and motion-controlling parts were also improved, resulting in faster data acquisition rate and less vibration of the system.m.

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Fabrication and Characterization of High $T_c$ $YBa_2Cu_3O_7-x$ Thick Films (YBCO 고온 초전도체 후막의 제작 및 특성 연구)

  • 정형진;박홍순;이전국;송진태
    • Journal of the Korean Ceramic Society
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    • v.27 no.3
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    • pp.299-310
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    • 1990
  • The fabrication of Y-Ba-Cu-O films and experimental factors affecting to characteristics of films are studied in detail. Superconducting thick films are fabricated by the screen printing method. The metal-citrate precursors are obtained simply by mixing of metal nitrate with citric acid. The particle size of heat treated powders is approximately 0.3-1${\mu}{\textrm}{m}$ and the thickness of film is estimated as 30-35${\mu}{\textrm}{m}$. According to the XRD analysis, the films sintered at 870-93$0^{\circ}C$ for 10min. -6hr with P(oxygen)=1atm has the unique orthorhombic crystal symmetry indicating the 123 phae. Tc, onset is determined around 92-87。K, but it shows semiconducting behavior probably due to the oxygen deficiency in the lattice, porosity and impurities in films. Extrapolated Tc, zero is estimated as 76-50。K. For films sintered at 90$0^{\circ}C$ for 1hr, superconducting properties are observed with the room temperature resistivity of 0.025$\Omega$.cm Tc, onset at 88。K and Tc, zero at 63。K.

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Electrophoretic Deposition of YBCO powder in mixed suspension solution of iso-prophanol and iso-buthanol (이소프로판올과 이소부탄올 용매에서의 YBCO 분말 영동전착)

  • Soh, Dae-Wha;Li, Ying-Mei;Park, Jung-Cheul;N., Korobova
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.288-291
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    • 2001
  • It is very important to select suspension solution for forming electrophoretic deposited YBCO thick mm, because it is heavily affected to its superconducting properties. In this paper, high-temperature superconductor films of $YBa_{2}Cu_{3}O_{7-x}$ were fabricated by electrophoretic deposition (EPD) from alcohol-based suspension such as iso-propanol, iso-butanol, and their mixture. For the formation of YBCO dense and adherent coating on a silver wire by EPD, 1 % PEG(1000) 2 ml, as a additive for making their surface crack-free, was used for electrophoresis. As a results, the cracks were considerably decreased and the superconducting critical current density $(J_e)$ without/with PEG was $1200A/cm^2$ and $2020A/cm^2$, which films deposited in mix iso-propanol and iso-butanol suspension.

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Fabrication of Superconducting Narrow Bandpass Filters with Parallel Microstrip Line (마이크로스트립 평행결합선을 이용한 초전도 협대역 필터의 제작)

  • Park, Joo-Hyung;Lee, Sang-Yeol;Yoon, Hyung-Kuk;Yoon, Young-Joong
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1549-1551
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    • 1998
  • We have designed and developed narrow bandpass multipole filters for satellite communication using $YBa_2Cu_3O_{7-x}$(YBCO) thin films on MgO substrates. The superconducting film used in this study was prepared by laser ablation on one side polished MgO (100) substrates. A Nd:YAG laser was used to fabricate YBCO thin films. The wave length of the laser was 355 nm. The laser beam was focused onto a YBCO target rotating linearly to avoid deep craters that may eject macroscopic YBCO particles. The YBCO films were grown at $750^{\circ}C$ in the oxygen partial pressure of 200 mTorr. The deposited YBCO thin films were patterned by conventional wet-etching method. The transition temperatures of YBCO thin films were 85 - 88 K and the film thicknesses were about 5,000 $\AA$. By comparing the performances of normal-metal filters and YBCO filters, we observed that superconducting YBCO multipole filters have been showed superior performances at 77 K.

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Structural and Electrical Properties of Semiconducting YBCO Thin Film Annealed at Various Temperatures for Uncooled Infrared Sensor Application (비냉각형 적외선 센서로 응용하기 위한 반도성 YBa2Cu3O6+x 박막의 열처리 온도에 따른 구조적 전기적 특성)

  • Lee, Tae-Ho;Lee, Sung-Gap;Yeo, Jin-Ho;Jung, Hye-Rin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.10
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    • pp.731-735
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    • 2013
  • YBCO thin films on $SiO_2$/Si substrate were fabricated by spin-coaing of an alkoxide-derived precursor and heat treatment. The structural and electrical properties of the YBCO films were investigated as functions of annealing temperature at $600{\sim}800^{\circ}C$. Although YBCO single phase was not synthesized, dense films of YBCO matrix phase and minor second phases have been successfully fabricated at the annealing temperatures of $650{\sim}800^{\circ}C$. Thickness and temperature coefficient of resistance (TCR) of YBCO thin films with annealing temperature of $750^{\circ}C$ were 0.31 ${\mu}m$ and $-2.92%/^{\circ}C$, respectively.

Design and Characterization of HTS antenna array with sequential rotation array (순차적 순환배열을 이용한 고온초전도 배열 안테나 설계 및 특성해석)

  • Chung, D.C.;Hwang, J.S.;Kim, Y.M.;Choi, H.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.05a
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    • pp.77-81
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    • 2006
  • We report the performance of a four-element, 11.67 GHz, high-Tc superconducting (HTS) microstrip antenna array with corporate feed network and circular polarization for direct broadcasting satellite (DBS) system. Our array antennas were designed and built on a 0.5 mm thick MgO substrate. To compare the superconducting antennas with normal conducting counterpart, One antenna pattern was fabricated from gold thin film, and a second pattern was fabricated from $YBa_2Cu_3O_{7-x}$ (YBCO) superconducting thin film. To improve the axial ratio of circularly polarized arrays, sequential rotation technique were used. Efficiency, radiation pattern, return loss and bandwidth were measured for both antennas at room temperature and at cryogenic temperature. The array produced good circular polarization, and the gain of the array at 77 K, relative to a copper array at room temperature was approximately 1.54 dB. The measured return loss of our HTS antenna array was 35.79 dB at the resonant frequency of 11.67 GHz and The total effective bandwidth was about 3.4 %. The results showed that high-temperature superconductors, when used in microstrip arrays, improved the efficiency of the HTS antenna array for circularly polarization.

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Study on HTS Antenna Array with Circularly Polarization for DBS Receiver (직접 위성방송 수신용 원편파 HTS 배열 안테나 관한 연구)

  • 정동철;윤창훈;최효상
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.7
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    • pp.776-781
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    • 2004
  • We report the performance of a four-element, 11.67 GHz, $high-{T}_c$ superconducting (HTS) microstrip antenna array with corporate feed network. The HTS antenna array used in this work had a circular polarization for direct broadcasting satellite (DBS) system. Our array antennas were designed and built on a 0.5 mm thick MgO substrate. To compare the superconducting antennas with normal conducting counterpart, One antenna pattern was fabricated from gold thin film, and a second pattern was fabricated from ${YBa}_2{Cu}_3{O}_7-x(YBCO)$ superconducting thin film. To improve the axial ratio of circularly polarized arrays, sequential rotation technique were used. Efficiency, radiation pattern, return loss and bandwidth were measured for both antennas at cryogenic temperature and room temperature. The array produced good circular polarization, and the gain of the array at 77 K, relative to a copper array at room temperature was approximately 1.54 dB. The measured return loss of our HTS antenna array was 35.79 dB at the resonant frequency of 11.67 GHz and The total effective bandwidth was about 3.4 %. The results showed that high-temperature superconductors, when used in microstrip arrays, improved the efficiency of the HTS antenna array for circularly polarization.