• Title/Summary/Keyword: bi-polarization

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Preparation and characterization of SrBi$_{2}$Ta$_{2}$ $O_{9}$ ferroelectric thin films for nonvolatile memory (비휘발성 메모리용 SrBi$_{2}$Ta$_{2}$ $O_{9}$강유전체 박막의 제조 및 특성연구)

  • 장호정;서광종;장기근
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.3
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    • pp.39-45
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    • 1998
  • SrBi$_{2}$Ta$_{2}$O$_{9}$ (SBT) ferroelectric thin films for nonvolatile memory were prepared on Pt/Ti/SiO$_{2}$/Si and RuO$_{2}$/SiO$_{2}$/Si substrates by RF magnetron sputtering. The dependences of crystalline and electrical properties on the lower electrode type(Pt and RuO$_{2}$) and the annealing temperatures were investigated. SBT films regardless of their electrode types showed typeical Bi layered peroviskite crystal structures. The crystalline quality of as-deposited SBT films was improved by the rapid thermal annealing at 650.deg. C for 30 sec. The remanetn polarization of 2Pr (Pr+-Pr-) of the annealed SBT films deposited on Pt/Ti/SiO$_{2}$/Si substrates were about 11 .mu.C/cm$^{2}$ and 3 .mu.C/cm$^{2}$, respectively. The leakage currents at 3 V bias voltage were about 0.8 .mu.A/cm$^{2}$ for SBT/ Pt/Ti/SiO$_{2}$/Si and about 1 .mu.A/cm$^{2}$ for SBT/RuO$_{2}$/SiO$_{2}$/Si sample. SBT films annealed at 650 .deg. C showed no degradation in Pr values after 10$^{11}$ polarization switching cycles, indicating good fatigue properties. In addition, for SBT samples deposited on Pt/Ti/SiO$_{2}$/Si, Pr values increased to more than that of initial state, suggesting the increament of leakage current caused by repeated polarization.

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Portable Metamaterial Structure Antenna for Dual-Band and Polarization-Reconfigurability

  • Lee, Changhyeong;Han, Dajung;Park, Heejun;Kahng, Sungtek
    • Journal of Satellite, Information and Communications
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    • v.11 no.3
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    • pp.127-132
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    • 2016
  • This paper presents the design of a palm-sized metamaterial antenna system having reconfigurable polarization as well as dual-band characteristics. Basically, three antennas are laid by 45 degrees in order and excited by a compact metamaterial dual-band power-divider of the in-phase outputs, and the radiated fields of the antennas are mixed to turn the vector of the polarization to another. The validity of the proposed method is verified by observing the in-phase outputs from the odd-numbered power-dividing device for both 900 MHz and 2.4 GHz, and checking the changeable polarization with the antenna gain over 2 dBi for all the polarizations.

The Research of Single Fed Broadband Planar Array Antenna with Modified Stacked-Structure using Circular Polarization (변형된 적층구조를 갖는 단일급전방식의 광대역 평판형 배열안테나 연구)

  • 정영배;이영환;문정익;박성욱;하재권
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.6
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    • pp.919-930
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    • 2001
  • This paper presents a wideband technique of impedance and axial-ratio bandwidth which uses the stacked planar array structure through optimum design of sub-polarization generating sections and parasitic patch. So, the effect of the dual-resonance characteristic can contribute to the bandwidth expansion of single fed planar array antenna using circular polarization which doesn\`t hire previous bandwidth expansion technique. The antenna can be used as a dual-band antenna by adjusting the resonance frequencies as well, and then the antenna is designed and fabricated in the frequency band of domestic satellite-TV service. This antenna has the performance of 9.7 % impedance bandwidth and 24 dBi of antenna gain. And it has also 2.8 % and 1.4 % of 3 dB Axial-ratio bandwidth at 11.4 GHz and 11.8 GHz respectively.

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Dual-Polarized 2 X 2 Array Antenna for Wireless LAN (무선 LAN용 이중 편파 2 X 2 배열 안테나)

  • 송성찬;이택경
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.7
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    • pp.635-643
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    • 2004
  • In this paper, dual-polarized 2${\times}$2 array antenna is designed and fabricated for the polarization diversity applications in wireless LAN system. For the improved bandwidth and isolation characteristics, the aperture coupled feeding and the L-shaped probe feeding are employed for each polarization. The measured bandwidths of the fabricated antenna are 210MHz for aperture coupled feeding and 280MHz for L-shaped probe feeding. The isolation for two ports is -40dB and the antenna gain is measured as 14.3${\pm}$0.2dBi in the operating frequency band of wireless LAN.

Effect of Annealing Temperature on the Properties of Sputtered Bi3.25La0.75Ti3O12 Thin Films

  • Kang, Hyunil;Song, Joontae
    • Transactions on Electrical and Electronic Materials
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    • v.14 no.3
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    • pp.130-132
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    • 2013
  • $Bi_{3.25}La_{0.75}Ti_3O_{12}$(BLT) thin films were prepared on the Pt(150 nm)/Ti(50 nm)/$SiO_2$/Si substrate using the rf magnetron sputtering method. The BLT thin films were annealed at temperatures ranging from $600^{\circ}C$ to $750^{\circ}C$ using the rapid thermal annealing. The structure and surface morphology of the thin films were characterized by x-ray diffraction and field emission scanning electron microscopy. The hysteresis loop of the BLT thin films showed that the remanent polarization (2Pr) of the film annealed at $700^{\circ}C$ was 10.92 ${\mu}C/cm^2$. The fatigue characteristic of the BLT thin film annealed at $700^{\circ}C$ was shown change polarization up to $1.2{\times}10^9$ switching cycles. We confirmed the excellent remnant polarization (Pr) and fatigue properties compared with other fabrication methods and suggested a good method for BLT thin films fabrications.

Characteristic Improvement & Design of Dual Polarization Wideband Single Element Antenna for IMT-2000 Base Station (IMT-2000 기지국용 이중 편파를 위한 광대역 단일 소자 안테나 설계 및 특성 개선)

  • Jang, Won-Ho;Park, Joo-Sung;Tae, Jae-Hoon;Lee, Yun-Hyun
    • Journal of Advanced Navigation Technology
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    • v.6 no.3
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    • pp.251-257
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    • 2002
  • Design and characteristic improvement of existing folded dipole antenna is presented to adopt W-CDMA(1.885~2.170 GHz) wideband antenna radiators. The antenna structure has +/- 45 degrees dual polarization. In order to overcome the narrow bandwidth and low gain characteristic typical of the microstrip antenna, double layered structure was employed. The antenna achieved below - 20 dB reflection coefficients each ports, - 20 dB of port isolation, above 7 dBi of gain, providing evidence that the proposed design can be used in the W-CDMA service frequency band antenna.

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Polarization properties of SBT capacitor with annealing temperatures (열처리에 따른 SBT 캐패시터의 분극특성)

  • Cho, C.N.;Kim, J.S.;Shin, C.G.;Chung, I.H.;Lee, S.G.;Lee, D.G.;Jung, D.H.;Kim, C.H.;Lee, J.U.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.09a
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    • pp.9-12
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    • 2001
  • The $Sr_{0.8}Bi_{2.4}Ta_2O_9(SBT)$ thin films are deposited on Pt-coated electrode($Pt/TiO_2/SiO_2/Si$) using RF magnetron sputtering method. With increasing post-annealing temperature from $600[^{\circ}C]$ to $850[^{\circ}C]$, Bi-layered perovskite phase was crystallized above $650[^{\circ}C]$. The maximum remanent polarization and the coercive electric field is 11.60[${\mu}C/cm^{2}$] 48[kV/cm] respectively. The leakage current density of SBT capacitor at post-annealing temperature of $750[^{\circ}C]$ is $1.01{\times}10^{-8}A/cm^2$ at 100[kV/cm]

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Design and Fabrication of LHCP Antenna for UHF RFID reader (UHF RFID 리더기용 LHCP 안테나 설계 및 제작)

  • Park, Sung-Il;Kim, Sun-Il;Ko, Young-Hyuk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.1
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    • pp.23-30
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    • 2010
  • In this paper, a design for the 900MHz bandwidth RFID reader antenna with circular polarization is proposed and experimentally investigated. The 900MHz bandwidth RFID reader antenna is proposed as a simple radiator with loading capacitor to generate LHCP(Left Hand Circular Polarization). Also, the design and fabrication of antenna has the returnloss of -32.28dB at the center frequency of 1010MHz and Bandwidth of 12.5% at 905Hz~1030MHz. Proposed LHCP antenna of maximum gain is 6dBi and satisfy axial ratio based on 2. From the measured result, axial ratios based on 2 are observed at the operating frequencies. The proposed antenna is suitable for RFID applications in wireless communications.

Fabrecation and Characterization of $SrBi_2TaNbO_9$ Ferroelectric Thin Film Prepared by Sol-Gel Method (SOL-GEL법을 이용한 $SrBi_2TaNbO_9$ 강유전성 박막 제조 및 특성 평가)

  • 이진한;박상준;장건익
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.94-98
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    • 2000
  • Polycrystalline SBTN ferroelectric thin films were prepared by sol-gel method with various Nb mole ratios on Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperatures and characterized in terms of phase and microstructure. Relatively a well saturated hysteresis pattern was obtained at x =0.2 in S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin films. At an applied voltage of 5V, the dielectric constant ($\varepsilon$$_{r}$) and dissipation factor (tan $\delta$) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin film (x=0.2) were about 236.2 and 0.034. Measured remanent polarization (2Pr) and coercive field (Ec) were 4.28C/c $m_2$, and 38.88kv/cm respectively. No fatigue was observed up to 6$\times$10$_{10}$ switching cycles at 5V and the normalized polarization reduced by a factor of only 4%.%. 4%.%. 4%.%.%.%.%.

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Design of Circularly Polarization Patch Array Antenna for DSRC (DSRC 통신을 위한 원형 편파 패치 배열 안테나 설계)

  • Kim, Hyun-Chul;Jung, Jin-Woo;Lee, Hyeon-Jin;Lim, Yeong-Seog
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.2
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    • pp.144-150
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    • 2012
  • In this paper, circularly polarization patch array antenna of RSE(Road-side Equipment) base station for DSRC(Dedicated Short Range Communication) of ITS(Intelligent Transport System) is proposed. The antenna of RSE base station for DSRC is designed to operate circularly polarization to receive reflected signal from multiplex path effectively. The proposed antenna consisted of microstrip patch and feed line, the slit is inserted in the proximity of the slot of feed structure to generate circularly polarization. The $2{\times}2$ array structure is designed to satisfying gain that DSRC RSE base station antenna required. Measured impedance bandwidth and axial-ratio bandwidth are satisfied by all DSRC band of 5.795~5.855 GHz. Vertical and horizontal HPBW of the proposed antenna are both about 43 degrees, it showed gain characteristic of about 11.21 dBi.