• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.873-874
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• 2015

본 논문에서는 24~77GHz 대역의 충돌 방지 레이더 센서를 이용한 차량 충돌 방지 알고리즘을 제안한다. 제안한 알고리즘은 센서로 부터 측정한 전압을 이용하여 전/후/좌/우의 차량의 접근 정보를 획득하고 이를 효율적으로 이용하여 다양한 상황에 따른 차량충돌방지를 할 수 있도록 구현되어 있다. 제안한 차량 충돌방지 알고리즘은 운행 중인 속도를 기반으로 속도구간별 운행정보를 계산하여 충돌방지를 실행한다. 본 연구에서 구현한 차량 충돌 방지 알고리즘은 차량 주행에서 좌우 차량충돌 없이 효율적으로 운행하는 특성을 보였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.77-82
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• 2017

As frequencies increase to the millimeter wave bands the cross sections of wave guides become smaller than a few millimeters, which cause sapatial problems in realization of spatial combining power amplifiers. In this paper we intented to overcome the problem by widening the width of wave guides using horn antenna principles. We designed a widened rectangular wave guide for using in spatial combining power amplifier in 60GHz ISM band(57-64GHz), and we installed Antipodal transition in the widened wave guide, and then we characterized it as a spatial combining power amplifier. For the compatibility of WR15 standard wave guide, we widened the width of WR15 to 7mm using principle of H-plane sectoral horn antenna and then installed 3 slots of back to back Antipodal transition. The designed spatial combining power amplifier showed good characteristics of return loss less than -22.4dB and insertion loss less than 0.53dB. However, as widening the width of the wave guide, additional modes such as $TE_{20}$, $TE_{30}$ in addition to $TE_{10}$ were accurred in the bandwidth of WR15, which restricted the bandwidth and widening of the width of the wave guide.

• Journal of the Korean Magnetics Society
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• v.9 no.1
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• pp.7-16
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• 1999

Stoichiometric and nonstoichiometric $Y_{3-x}Fe_{5+x}O_{12})$ polycrystalline samples (x=0.00, 0.05, 0.10, 0.30, -0.05, -0.10, -0.30) were prepared by solid state reaction method. The magnetic properties of the sample were investigated by FMR (ferromagnetic resonance) technique at microwave frequency 5.11 GHz (G-band) and 23.39 GHz (K-band) respectively. The spectroscopic splitting factor g were estimated to be 2.04~2.35 from the derivative absorption lines. As the samples became yttrium $(Y^{3+})$ excess and iron $(Fe^{3+})$ excess, Magnetizations were decreased. But resonance linewidth were increased. To investigate the anisotropy, the angular dependence of resonance magnetic fields were measured. Angular dependence of effective magnetizations were measured by FMR from 77 K to 300 K at K-band microwave frequency (23.39 GHz) and the saturation magnetizations were measured by VSM. The Bloch coefficients B and C were determined by fitting. $M_{eff}(0)$ was obtained by the extrapolation from 80 K. From this result, the spin wave stiffness constant D $(about\; 162~206 \;eV{\AA}^2)$and average square range of exchange interaction $$$(about \;5.84~12.13\;{\AA}^2)$ were determined.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.102-111
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• 2004

신속하고 편리한 현대사회의 핵심에는 정보통신 기술이 자리하고 있다. 근래에는 개인용 휴대통신단말기와 무선인터넷 접속을 위한 무선 LAN(local area network) 등 무선통신기기의 사용주파수가 높아져서 1 GHz이상의 주파수 대역에서 불필요한 전자파 발생이 증가하고 있다. 전자파장해 방지 및 내성시험에 관한 국제규격은 국제 전기 기술위원회(IEC, International Electrotechnical Commission) 산하의 민간 전문가들로 구성된 기술위원회(TC, Technical Committee) 77과 국제무선장해특별위원회(CISPR, International Special Committee on Radio Interference)에서 정해진다. TC 17과 CISPR는 많은 심의를 거쳐 1 GHz 이상 주파수 대역의 전자파장해 국제규격을 일부 완성하였으며, 지금도 규격개정 과정에서 활발하게 토의하고 있다. (중략)

• ETRI Journal
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• v.31 no.3
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• pp.324-326
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• 2009

We present the design of a compact microstrip lowpass filter with a wide stopband which is up to ten times the cutoff frequency. The filter is based on a coupled-line configuration and shunt open stubs. The open stubs create additional transmission zeros, which are used to extend the stopband of the filter without any additional components or cascaded units. A prototype lowpass filter with a 3 dB cutoff frequency of 0.428 GHz and a 15 dB stopband extended up to 4.77 GHz is fabricated to validate the theoretical predictions.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.535-541
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• 2016

A low phase noise META-VCO based-on meta-structure was designed using 65 nm CMOS process. We used a meta-structure to get good phase noise characteristics. The measured phase noises are -67.8 dBc/Hz, -96.37 dBc/Hz, and -107.37 dBc/Hz at 100 kHz, 1 MHz, and 10 MHz offset respectively. The META-VCO operates 8.45~8.77 GHz according to VCTRL, and the output power is -19.12 dBm. The power consumption is 28 mW with 1.2-V supply voltage. The calculated FOM is -140.76 dBc/Hz.

• Journal of the Korea Society of Computer and Information
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• v.27 no.3
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• pp.71-77
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• 2022

In this paper, we propose 1×2 array antenna with dual linear polarization characteristics for mmWave band operation. The proposed antenna is designed two microstirp feeding structure and FR-4 substrate, which is thickness 0.4 mm, and the dielectric constant is 4.3. The size of 1×2 array antenna is 2.33 mm×2.33 mm, and total size of array antenna is 13.0 mm×6.90 mm. From the fabrication and measurement results, bandwidths of 1.13 GHz (28.52~29.65 GHz) for port 1 and 1.08 GHz (28.45~29.53 GHz) for port 2 were obtained based on the impedance bandwidth. Cross polarization ratios are obtained from 7.68 dBi to 16.90 dBi in case of vertical polarization, and from 7.46 dBi to 15.97 dBi in case of horizontal polarization for input port 1, respectively. Also, cross polarization ratios are obtained from 8.59 dBi to 13.72 dBi in case of vertical polarization and from 9.03 dB to 14.0 dB in case of horizontal polarization for input port 2, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.885-894
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• 2015

In this paper, it can be applied to a walkie-talkie, the RFID / USN 920 MHz band(917~923.5 MHz) and WiFi 2.4GHz band(2.4~2.483 5GHz) return loss is 10 dB over the band, on-board dual band with omni-directional radiation characteristics is proposed. The basic structure designed antenna is used meander monopole antenna. It was used as double stubs and tabs for antenna designs that meet the criteria proposed. The double stub and the tab affects the reactance of the antenna to form a common-mode and differential-mode in the stub to improve the antenna characteristics and return loss in the bandwidth, gain and radiation characteristics. The system size of walkie-talkie is $52{\times}77mm^2$, the size of the antenna is limited to $52{\times}15mm^2$, the thickness of FR4 dielectric substrate is 0.8 mm, FR4 dielectric constant 4.4 is used. For experimental results, the return loss is measured more than 10 dB, the maximum gain is measured 1.95 dB, the maximum bandwidth is measured 360 MHz, the radiation characteristic is measured omni-directional. By a walkie-talkie terminal design applying the results of the paper, the handset's price competitiveness and production efficiency can be improved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.227-247
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• 2015

An X-band $8{\times}16$ dual-polarized active phased array antenna system has been implemented based on the substrate integrated waveguide(SIW) technology having low propagation loss, complete EM shielding, and high power handling characteristics. Compared with the microstrip case, 1 dB less is the measured insertion loss(0.65 dB) of the 16-way SIW power distribution network and doubled(3 dB improved) is the measured radiation efficiency(73 %) of the SIW sub-array($1{\times}16$) antenna element. These significant improvements of the power division loss and the radiation efficiency using the SIW, save more than 30 % of the total power consumption, in the active phased array antenna systems, through substantial reduction of the maximum output power(P1 dB) of the high power amplifiers. Using the X-band $8{\times}16$ dual-polarized active phased array antenna system fabricated by the SIW technology, the main radiation beam has been steered by 0, 5, 9, and 18 degrees in the accuracy of 2 degree maximum deviation by simply generating the theoretical control vectors. Performing thermal cycle and vacuum tests, we have found that the SIW array antenna system be eligible for the space environment qualification. We expect that the high efficiency SIW array antenna system be very effective for high performance radar systems, massive MIMO for 5G mobile systems, and various millimeter-wave systems(60 GHz WPAN, 77 GHz automotive radars, high speed digital transmission systems).