• Title/Summary/Keyword: quasi-microwave

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Quasi-static Analysis on the Effect of the Finite Metal with the Anisotropic Grooved Dielectric in Microstrip Lines

  • Hong Ic-Pyo
    • Journal of the Microelectronics and Packaging Society
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    • v.12 no.1 s.34
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    • pp.17-20
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    • 2005
  • In this paper, we presented the quasi-static characteristics of novel microstrip lines with anisotropic grooved dielectric in finite metal. A quasi-static mode-matching method has been used to analyze this new structure and the simulation results are validated through comparison with other available results. The results in this paper show that it is possible to control the propagation characteristics of microstrip lines with the use of anisotropic grooved dielectric in finite metal. Also anisotropic grooved dielectric in microstrip line can be newly added to the design parameters of high performance three dimensional monolithic microwave circuits and other microwave applications.

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Microwave Absorbing Properties of Rubber Composites Containing Soft Magnetic Fe-Alloy Particles (철계 연자성 합금 분말을 함유한 고무 복합재의 전파흡수특성)

  • Cho, Han-Shin;Kim, Sung-Soo
    • Journal of Powder Materials
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    • v.20 no.2
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    • pp.125-128
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    • 2013
  • Magnetic and dielectric properties of rubber composites are controlled by using two kinds of high-permeability metal particles with different electrical conductivity (Sendust, Permalloy), and their effect on microwave absorbance has been investigated, focusing on the quasi-microwave frequency band (0.8-2 GHz). Noise absorbing sheets are composite materials of magnetic flake particles of high aspect ratio dispersed in polymer matrix with various filler amount of 80-90 wt.%. The frequency dispersion and magnitude of complex permeability is almost the same for Sendust and Permalloy composite specimens. However, the complex permittivity of the Permalloy composite (${{\varepsilon}_r}^{\prime}{\simeq}250$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}50$) is much greater than that of Sendust composite (${{\varepsilon}_r}^{\prime}{\simeq}70$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}0$). Due to the large dielectric permittivity of Permalloy composite, the absorbing band is shifted to lower frequency region. However, the investigation of impedance matching reveals that the magnetic permeability is still small to satisfy the zero-reflected condition at the quasi-microwave frequency band, resulting in a small microwave absorbance lower than 10 dB.

Two-Layered Microwave Absorber of Ferrite and Carbon Fiber Composite Substrate

  • Han-Shin Cho;Sung-Soo Kim
    • Journal of Magnetics
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    • v.3 no.2
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    • pp.64-67
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    • 1998
  • Microwave absorbing properties of ferrite-epoxy composite (absorbing layer) attached on the carbon fiber polymer composite (reflective substrate) are analyzed on the basis of wave propagation theory. A modified equation for wave-impedance-matching at the front surface of absorbing layer including the effect of electrical properties of the quasi-conducting substrate is proposed. Based on this analysis, the frequency and layer dimension that produce zero-reflection can be estimated from the intrinsic material properties of the obsorbing layer and the substrate. It is demonstrated that the microwave reflectivity of carbon fiber composite has a strong influence on the microwave absorbance of front magnetic layer.

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Electromagnetic Properties of Siver Coated Iron based Alloy Powders Prepared by Chemical Reduction Method

  • Lee, Byoung-Yoon;Lee, Jae-Wook;Yun, Yeo-Chun;Jeong, In-Bum;Moon, Joo-Ho
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1213-1214
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    • 2006
  • The synthesis of silver coated iron base alloy (Sendust : Fe-Si-Al) powder having the both effects of shielding and suppressing of electromagnetic wave was studied. Depending on thickness of silver coating layer, the electromagnetic properties of the dispersed particles complexed with organic binder were examined. It is proposed that the silver coated sendust flake powders with controlled electrical properties and thickness can be used as thin microwave absorbers in quasi-microwave frequency band.

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Optimum Design of EHF CPW using FDTD (시간영역유한차분법을 이용한 극초고주파용 CPW의 최적화 설계)

  • Jang, In-Bum;Lee, Joon-ung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.12
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    • pp.1129-1132
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    • 2005
  • The purpose of this reserch is to establish the new design technology for microwave Coplanar structure. The components in microwave circuit are classified to transmission devices, EM devices, and quasi-TEM devices. After design of these devices, we analyzed these CPWs electromagnetically using FDTD method, and suggested optimum CPW structure. In oder to realize a CPW module up to 30 GHz-100 GHz band, we research on a technology of 3-dimensional microwave CPW, and GaAs substrate with Si layer for ohmic loss. As a result this research, we suppressed the leakage, resonance, coupling, and radiation of CPW EMI, and improved resonance quality of CPW.

Microwave Absorbing Properties of Fe-Si-Al Alloy Flaky Powder-Rubber Composites (Fe-Si-Al 합금 분말 · 고무 복합 자성체의 전파 흡수 특성)

  • Lee Kyung-Sub;Yoon Yeo-Choon;Choi Gwang-Bo;Kim Sung-Soo;Lee Jun-Young
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.2 s.93
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    • pp.228-234
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    • 2005
  • A magnetic composite as noise absorber of quasi-microwave band was developed. The Fe-Si-Al alloy powder were forged by attrition mill to get flaky shape. The magnetic composite sheet was fabricated in which powders are dispersed in polymer and aligned in the direction perpendicular to electromagnetic wave propagation. The permittivity of magnetic composite is increased as forging time increasing, while the permeability is decreased slightly. The maximum attenuation peak of reflection loss is shifted to lower fiequency range as milling time increasing, and the value of maximum attenuation peak is to get smaller gradually. From these result, we could designed a noise absorber sheet (t=1.0 mm) for quasi-microwave band, which is impedance matched at 1.4 GHz with respect to -8.2 dB reflection 1055.

AN ALTERNATIVE COSMOLOGY

  • NARLIKAR JAYANT V.
    • Journal of The Korean Astronomical Society
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    • v.29 no.spc1
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    • pp.1-5
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    • 1996
  • Recent discussions of observational constraints on the standard hot big bang model are reviewed and it is argued that now there is room for considering alternative cosmologies. The quasi-steady state cosmology is briefly described. This model seems to explain most of the observed features of the universe, including the m-z relation, radio source count, the light nuclear abundances and the microwave background.

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Pulse Width and Pulse Frequency Modulated Soft Commutation Inverter Type AC-DC Power Converter with Lowered Utility 200V AC Grid Side Harmonic Current Components

  • Matsushige T.;Ishitobi M.;Nakaoka M.;Bessyo D.;Yamashita H.;Omori H.;Terai H.
    • Proceedings of the KIPE Conference
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    • 2001.10a
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    • pp.484-488
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    • 2001
  • The grid voltage of commercial utility power source hi Japan and USA is 100rms, but in China and European countries, it is 200rms. In recent years, In Japan 200Vrms out putted single phase three wire system begins to be used for high power applications. In 100Vrms utility AC power applications and systems, an active voltage clamped quasi-resonant Inverter circuit topology using IGBTs has been effectively used so far for the consumer microwave oven. In this paper, presented is a half bridge type voltage-clamped high-frequency Inverter type AC-DC converter using which is designed for consumer magnetron drive used as the consumer microwave oven in 200V utility AC power system. This zero voltage soft switching Inverter can use the same power rated switching semiconductor devices and three-winding high frequency transformer as those of the active voltage clamped quasi-resonant Inverter using the IGBTs that has already been used for 100V utility AC power source. The operating performances of the voltage source single ended push pull type Inverter are evaluated and discussed for consumer microwave oven. The harmonic line current components In the utility AC power side of the AC-DC power converter operating at ZVS­PWM strategy reduced and improved on the basis of sine wave like pulse frequency modulation and sine wave like pulse width modulation for the utility AC voltage source.

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Hydrometeors and Atmospheric Thermal Structure Derived from the Infrared and Microwave Satellite Observations: Infrared Interferometer Spectrometer (IRIS) and Microwave Sounding Unit (MSU) (적외선과 마이크로파 위성관측에서 유도된 대기물현상 및 대기 열적 상태: 적외선 간섭분광계 (IRIS)와 Microwave Sounding Unit)

  • Yoo, Jung-Moon;Song, Hee-Young;Lee, Hyun-A;Koo, Gyo-Sook
    • Atmosphere
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    • v.12 no.4
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    • pp.69-90
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    • 2002
  • The infrared and microwave satellite observations have been used to derive the information of hydrometeors (i.e., cloud and precipitation) and atmospheric temperature. The observations were made by the Nimbus-4 Infrared Interferometer Spectrometer (IRIS) in 1970, and by the Microwave Sounding Unit (MSU) during the period 1980-99, which had channel 1~4 (Chl~4). The IRIS, which has a field of view of ~100 km, has been utilized to examine the cirrus and marine stratus clouds. The cirrus and stratus distributions were obtained, respectively, based on the spectral difference in the infrared window region, and the absorption of water vapor and $CO_2$ in the spectral region $870-980cm^{-1}$. The MSU Ch1 data has been used for low tropospheric temperature and hydrometeors, while the Ch2, Ch3 and Ch4, respectively, for the thermal state of midtroposphere, tropopause, and lower stratosphere. The climatic aspects of El Ni$\tilde{n}$o, Quasi-Biennial Oscillation (QBO) and temperature trends over the globe are discussed with the MSU data. This study suggests that the IRIS and MSU data are useful for monitoring the hydrometeors and atmospheric thermal state in climate system.