• Title/Summary/Keyword: Band Stop

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Improved Performance of Microstrip Antenna using the Compact Photonic Band-gap Structures (소형 포토닉 밴드갭 구조를 이용한 마이크로스트립 안테나의 성능 향상)

  • Kim Young-Do;Lee Hong-Min
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.5 s.347
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    • pp.147-155
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    • 2006
  • In this paper, we propose a new Mushroom-like PBG concepts for designing with forbidden frequency band-gap at low frequency. These design rules are based on enhancing the capacitance per unit area using modified top-patch of mushroom PBG with no increase on the overall thickness of the substrate board. Also, in this paper, a new approach to suppress the surface wave from antenna is proposed by embedding compact mushroom PBG in the substrate. Comparisons between the results from a conventional patch antenna to a patch antenna on a PBG substrate show that the reduction in the surface wave level is remarkable. This can be observed in the radiation pattern and the maximum gain. The maximum gain for reference patch antenna is $6.43dB{\imath}$ at 5.37 GHz, while the maximum gain for the patch antenna with normal mushroom and vane mushroom PBG is $7.24dB{\imath}\;and\;7.53dB{\imath}$at 5.14 GHz. The back radiation is also considerably reduced; this will lead, of course, to an increase in the antenna efficiency.

Development of the Near Infrared Camera System for Astronomical Application

  • Moon, Bong-Kon
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.1
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    • pp.39.2-39.2
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    • 2010
  • In this paper, I present the domestic development of near infrared camera systems for the ground telescope and the space satellite. These systems are the first infrared instruments made for astronomical observation in Korea. KASINICS (KASI Near Infrared Camera System) was developed to be installed on the 1.8m telescope of the Bohyunsan Optical Astronomy Observatory (BOAO) in Korea. KASINICS is equipped with a $512{\times}512$ InSb array enable L band observations as well as J, H, and Ks bands. The field-of-view of the array is $3.3'{\times}3.3'$ with a resolution of 0.39"/pixel. It employs an Offner relay optical system providing a cold stop to eliminate thermal background emission from the telescope structures. From the test observation, limiting magnitudes are J=17.6, H=17.5, Ks=16.1 and L(narrow)=10.0 mag at a signal-to-noise ratio of 10 in an integration time of 100 s. MIRIS (Multi-purpose InfraRed Imaging System) is the main payload of the STSAT-3 in Korea. MIRIS Space Observation Camera (SOC) covers the observation wavelength from $0.9{\mu}m$ to $2.0{\mu}m$ with a wide field of view $3.67^{\circ}{\times}3.67^{\circ}$. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI of 30 layers, and GFRP pipe support in the system. Opto-mechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform the Galactic plane survey with narrow band filters (Pa $\alpha$ and Pa $\alpha$ continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

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A Study on Synthesis of The Low Pass NIC Filter (Low Pass NIC Filter 설계에 관한 고찰)

  • 이정한;이영수
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.4 no.1
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    • pp.13-21
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    • 1967
  • A low pass filter is synthesized with R, C and negative impedance converters(NIC). The filter has a 4-th order elliptic function, which gives best magnitude approximation with equi-ripple characteristics both in pass and stop band. And experimental investigations have been made on the effect of the anticipated deviation of the NIC conversion factor and of possible loaded operation. Through the study, it has been cocluded that: 1. For minimum pole-zero sensitivity with respect to the NIC conversion factor, the network of a parallel RC-NIC configuration is preferable and the Horowitz polynomial decomposition method is applied in the synthesis procedure. 2. A few percentage variation of the NIC conversion factor changes the frequency and amplitude characteristics of the filter by nearly negligible amount. 3. With a load resistance below the critical value, the filter turns into an oscillator.

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A Compact Lumped-Element Low-Pass Filter with Transmission Zeros

  • Lee, Byoung-Hwa;Park, Sang-Soo
    • Journal of electromagnetic engineering and science
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    • v.3 no.1
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    • pp.35-38
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    • 2003
  • In this paper, compact lumped-element low-pass filter structure with two transmission zeros at second and third harmonics is presented. The use of lumped-elements and transmission zeros can provide the advantages of compact size, sharp cutoff and wide stop-band frequency response. The proposed low-pass filter is a modified Chebyshev low-pass filter type and is implemented by the use of low temperature co-fired ceramic (LTCC) technology. This filter has been verified by both simulation and experiment. The simulated and experimental results agree very well.

A Design of Insulted Diagnosis Sensor for GIS (GIS 절연진단 센서 설계)

  • Choi, Eun-Hyuck;Kim, Gi-Chai;Lee, Kwang-Sik
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2005.11a
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    • pp.381-384
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    • 2005
  • If obstacle in GIS(Gas Insulted Switchgear), its affects are great are on the community and it is consequently demanded lots of difficulties to recover and repair. Accordingly, diagnosis techniques, that are able to prevent from accidents before they happen by providing more stable and highly reliable power effectively and finding sign of the accidents is very important A novel UHF(Ultra High Frequency)-microstrip antenna is presented. The measured impedance bandwidth of the proposed antenna is from 0.5[GHz] to 15[GHz] with the stop band from 0.5[GHz] to 10.7 [GHz] for VSWR<2. Form results of this study, The antenna is will play an important role for the sensor for insulation diagnosis system by UHF method of real site GIS and power equipment using SF$_6$ gas.

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Frequency response of Sensors for GIS insulation-diagnosis (GIS 절연진달을 위한 센서 구조별 주파수 특성)

  • Choi, Eun-Hyeok;Kim, Jung-Bae;Kim, Gi-Chai;Lee, Kwang-Sik
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2007.05a
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    • pp.413-416
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    • 2007
  • If obstacle in GIS(Gas Insulted Switchgear), its affects are great are on the community and it is consequently demanded lots of difficulities to recover and repair. Accordingly, diagnosis techniques, that are able to prevent from accidents before they happen by providing more stable and highly reliable power effectively and finding sign of the accidents is very important. The strip-senser measured impedance bandwidth of the proposed antenna is from 0.5[GHz] to 2.5[GHz] with the stop band from 0.5[GHz] to 1.7[GHz] for VSWR<2. The antenna is will play an important role for the senser for insulation diagnosis system by UHF method of real site GIS and power equipment using $SF_6$ gas.

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Design of M-Channel IIR Uniform DFT Filter Banks Using Recursive Digital Filters

  • Dehghani, M.J.;Aravind, R.;Prabhu, K.M.M.
    • ETRI Journal
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    • v.25 no.5
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    • pp.345-355
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    • 2003
  • In this paper, we propose a method for designing a class of M-channel, causal, stable, perfect reconstruction, infinite impulse response (IIR), and parallel uniform discrete Fourier transform (DFT) filter banks. It is based on a previously proposed structure by Martinez et al. [1] for IIR digital filter design for sampling rate reduction. The proposed filter bank has a modular structure and is therefore very well suited for VLSI implementation. Moreover, the current structure is more efficient in terms of computational complexity than the most general IIR DFT filter bank, and this results in a reduced computational complexity by more than 50% in both the critically sampled and oversampled cases. In the polyphase oversampled DFT filter bank case, we get flexible stop-band attenuation, which is also taken care of in the proposed algorithm.

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Precise response time measurement and analysis of liquid crystal displays

  • Glinel, David;Boher, Pierre;Leroux, Thierry
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.723-728
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    • 2006
  • In this paper, we present a new system, OPTISCOPE SA, especially designed for precise measurement of temporal behavior of LCD displays. We show that gray to gray level response time measurement requires a very sensitive and precise instrument and also that the capacity to measure luminance levels and gamma curve can be useful. Quite often, precise evaluation of LCD response time needs also use of low pass and stop band filters to suppress noise and flicker. Low pass filters affect the results but can be corrected for simple temporal behaviors. For complex temporal behaviors like those observed for overdriven LCDs, we show that direct adjustment of theoretical responses is much more efficient to get a complete picture of the temporal behavior of such displays.

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Investigation of Flying Characteristic of Sliders with Micro-actuator (마이크로 액추이에터를 장착한 슬라이더의 부상특성 연구)

  • 문재택;정구현;전종업;김대은
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.926-929
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    • 2000
  • As the track density of hard disk drives increases, there is a need for more precise actuation of the head. This can be accomplished by using a high band width micro-actuator. In this work, the flying characteristics of sliders with micro-actuators are investigated with the aim to optimize the head/disk interface performance of such sliders. Contact-start-stop, sweep, and flying height tests are performed and analyzed. The results show that the MEMS based micro-actuator mounted on a slider possess acceptable flying characteristics.

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Investigation of Flying Characteristics of Slider with Micro-actuator (마이크로 액추에이터를 장착한 슬라이더의 부상특성 연구)

  • Moon, Jae-Taek;Chung, Koo-Hyun;Kim, Dae-Eun;Jeon, Jong-Up
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.9
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    • pp.96-100
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    • 2001
  • As the track density of hard disk drives increases, there is a need for more precise actuation of the head. This can be accomplished by using a high band width micro-actuator. In this work, the flying characteristics of sliders with micro-actuators are investigated with the aim to optimize the head/disk interface performance of such sliders. Contact-start-stop, sweep, and flying height tests are performed and analyzed. The results show that the MEMS based micro-actuator mounted on a slider possess acceptable flying characteristics.

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