• Title, Summary, Keyword: Waveguide Arrays

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Evaluation of Local Loss Coefficients for Different Waveguide-Below-Cutoff (WBC) Arrays of Electromagnetic Pulse (EMP) Shied in Buildings (도파관 배열에 의한 국부저항계수 산정)

  • Pang, Seung Ki;Chae, Young Tae
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.7
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    • pp.366-372
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    • 2017
  • The objective of this study was to characterize Waveguide-Blow-Cutoff (WBC) array for Electromagnetic Pulse (EMP) shield in air duct or water pipe, the typical pathway of pulse in indoor space with critical electronic device. A numerical investigation with three different WBC designs (circular, rectangular, and hexagonal or honeycomb) was conducted to satisfy recommended shielding effectiveness (SE) levels from 80 dB to 140 dB. Pressure drop between upstream and downstream of EMP shields based on WBC arrays was also investigated to understand air flow feature in air duct of HVAC system. Results showed that honeycomb geometry outperformed other shapes in terms of reducing the depth of EMP shield, thus providing better air flow in duct path with lower local loss coefficient in HVAC system under SE requirements.

Evaluation of Air Flow Characteristics in accordance with Types of Waveguide-Below-Cutoff (WBC) Arrays and Their Shielding Effectiveness of Electromagnetic Pulse (EMP) (EMP 차폐를 위한 도파관 형상과 SE에 따른 유동 특성 평가)

  • Pang, Seung-Ki;Ahn, Hye-Rin;Yook, Jong-Gwan
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.12 no.3
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    • pp.1-8
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    • 2016
  • In this study, we evaluated the flow characteristics of various types of waveguide-below-cutoff (WBC) arrays and their shielding effectiveness (SE) of electromagnetic pulses (EMP) based on computational fluid dynamics (CFD). Three types of waveguides were selected for analysis: (1) grid type, (2) honeycomb type, and (3) multi-layer types (2-ply, 4-ply, 6-ply, and 8-ply). To analyze the air flow characteristics, the flow velocities in the longitudinal center of the WBC and the differential pressures between the WBC array inlet and outlet were evaluated. Consequently, we derive the following conclusions: (1) despite an increase in the inlet velocity, the pressure drop of the 6-ply multi-layer type did not significantly increase as compared to that of other types of waveguides (waveguide thickness of 0.1 mm, SE of 100 dB); (2) the grid and honeycomb type had the fastest flow rate of 17.5 m/s, which is approximately 2.5 m/s faster than that at the inlet (waveguide thickness of 1 mm, module size of 30 mm); and (3) the average pressure drop of the grid type waveguide is the lowest in the overall model, whereas that of the 8-ply is the highest (waveguide thickness of 1 mm, module size of 30 mm, and SE of 80, 100 dB).

Duality of Photonic Crystal Radiative Structures and Antenna Arrays

  • Bozorgi, Mahdieh;Granpayeh, Nosrat
    • Journal of the Optical Society of Korea
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    • v.14 no.4
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    • pp.438-443
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    • 2010
  • In this paper, behaviors of photonic crystal (PC) radiative structures and antenna arrays have been compared for two types of uniform and binomial excitations. Appropriate duality has been shown between them. These results can be generalized to other types of excitation and arrangement of photonic crystal radiative arrays such as linear, planar and circular arrays of three dimensional (3D) photonic crystal termination resonators. Using these results in designing photonic circuits has some advantages for shaping a particular radiative beam at the photonic crystal exit, for instance reducing the divergence angle of the main lobe in order to enhance the directivity, for better coupling, or for splitting the emitted beam, for dividing the output beam to the next devices in photonic integrated circuits (PIC). For analysis and simulation of the photonic crystal structures, the finite difference time domain (FDTD) method has been employed.

A Circularly Polarized Waveguide Narrow-wall Slot Array using a Single Layer Polarization Converter

  • Kim, Dong-Chul;Min, Kyeong-Sik
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.1
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    • pp.59-65
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    • 2000
  • This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value Problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

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X-ray Diffraction from X-ray Waveguide Arrays for Generation of Coherent X-ray

  • Park, Yong-Sung;Choi, Jae-Ho
    • Journal of the Optical Society of Korea
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    • v.14 no.4
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    • pp.333-336
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    • 2010
  • The generation of coherent x-ray beams by using a multi-slit diffraction phenomenon is presented. The mode-confinement conditions in the x-ray waveguide (XWG) needed to obtain single-mode beams are determined. The XWGs are stacked to form an XWG array. The core of the XWG array is used as a slit in an opaque screen, similar to those used for visible light. Diffraction patterns that interfered constructively in the XWG array are investigated based on multi-slit diffraction theory. The irradiance distributions are studied at on observation screen. The FWHM of diffracted x-ray spectra were between $1.67{\times}10^{-4}$ to $3.30{\times}10^{-5}$ radians which lead to a spot-size of a few tens of micrometers on the screen at distance of 1 m. The intensities decrease with increase in the period of the XWG array, i.e. a thicker cladding, due to growth of the higher-order diffraction peaks.

A Slot Away Antenna with a Simple Feed Structure for Broadband Multimedia Wireless Applications (단순한 급전 구조를 갖는 Broadband Multimedia Wireless System(BMWS)용 슬롯 배열 안테나)

  • 성영제;이정수;오순수;문종용;최원규;표철식;최재익;김영식
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.3
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    • pp.209-216
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    • 2003
  • We design and fabricate slot array antenna for BMWS(Broadband Multimedia Wireless System) applications. This paper presents a simple feed structure, which consists of two horns and a parallel-plate waveguide, because antennas operating at 40.5 GHz~43.5 GHz have considerable feeding losses. The simple feed structure has the advantages of high-efficiency and mass-production. The fabricated antenna has a gain of 25.8 dBi with a sidelobe level below -18 ㏈ and a 3 ㏈ beamwidth of approximately 3$^{\circ}$ in the E-plane. In case of H-plane, a 3 ㏈ beamwidth is 17$^{\circ}$ and a sidelobe level is suppressed to below -27 ㏈. The experimental results are in good agreement with the simulation results. The authors expect that narrow 3 ㏈ beamwidth is obtained by combining a few proposed slot array antennas in parallel.

Optical PCB and Packaging Technology (광 PCB 및 패키징 기술)

  • Ryu, Jin-Hwa;Kim, Dong-Min;Kim, Eung-Soo;Jeong, Myung-Yung
    • Journal of the Microelectronics and Packaging Society
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    • v.18 no.1
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    • pp.7-13
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    • 2011
  • According to increasing of data transfer rate, printed circuit board (PCB) is required improvement of transmission speed. Optical PCB and its packaging technology can be one of the solutions that overcome the limitations of conventional electrical PCB. The data transmission capacity will be increased 10 Tbps at 2015. To this end, studies on various OPCB technologies are being conducted. For cost-effective and high- performance OPCB, studies of optical coupling by polymer replication process are conducted. In this work, optical waveguide and optical fiber array block were sequentially fabricated by polymer pattern replication method. Using this method we successfully demonstrate low loss optical fiber coupling between optical waveguide and optical fiber arrays. And researches on flip chip bonding process and using electro-optic connectors for packaging are conducted.

Spatially Combined V-Band MMIC Coupled Oscillator Array in Waveguide (도파관 내에서 공간적으로 결합된 V-Band MMIC 결합 발진기 Array)

  • 최우열;김홍득;강경태;임정화;권영우
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.8
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    • pp.783-789
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    • 2002
  • In this paper, V-band MMIC coupled oscillator arrays are presented. In the proposed array, two push-pull patch antennas are synchronized by using strong electromagnetic coupling between two antennas. As a result, total size of the array is reduced and the array can be integrated in a single chip. To verify proposed array concept, two 1$\times$2 arrays are designed and fabricated using standard 0.15 um gate length pHEMT MMIC process. The circuits are mounted in an oversized waveguide and measured. The first array shows 0.5 dBm at 56.372 GHz and the second one has an output of 5.85 dBm at 60.147 GHz.

Electromagnetic Pulse (EMP) Shielding Effectiveness of Waveguide-Below-Cutoff (WBC) Arrays Installed in Generator Exhaust Chimney and its Effects on Gas Velocity (도파관 배열이 설치된 비상발전기 연도의 유속 예측 및 EMP 차폐평가)

  • Pang, Seung-Ki;Kim, Jae-Hun;Yook, Jong-Gwan;Kim, Yuna;Kim, Sangin;Kim, Suk-Bong
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.12 no.1
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    • pp.1-6
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    • 2016
  • Characteristics of exhaust from chimney of electricity generator are analyzed based on CFD when Waveguide-Below-Cutoff (WBC) array is installed in order to achieve the certain level of electromagnetic pulse (EMP) shielding. The main purpose is prediction of average and maximum velocity of exhaust. The results reveal that: 1) When the specification of waveguide is given as 80-diameter, 400-length, and the gap of 20 mm, the shielding effectiveness (SE) is 140dB. The average and maximum velocity of exhaust in the chimney with WBC Array can be represented as exponential functions. 2) As the number of WBC increases, the velocity in the chimney dwindles. 3) Under the situation that WBC with 80 mm diameter is located at intervals of 20 mm, the average velocity can be approximated by $25.5344{\times}e^{(-0.0098{\times}N_{WBC})}$ with input velocity of 15 m/s. In addition, the determination coefficient is 0.915, which is sufficiently high.

Lanthanide-Cored Supramolecular Systems with Highly Efficient Light-Harvesting Dendritic Arrays towards Tomorrow′s Information Technology

  • Kim, Hwan-Kyu;Roh, Soo-Gyun;Hong, Kyong-Soo;Ka, Jae-Won;Baek, Nam-Seob;Oh, Jae-Buem;Nah, Min-Kook;Cha, Yun-Hui;Jin Ko
    • Macromolecular research
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    • v.11 no.3
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    • pp.133-145
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    • 2003
  • We have developed novel lanthanide-cored supramolecular systems with highly efficient light-harvesting dendritic arrays for integrated planar waveguide-typed amplifiers. Er$^{3+}$ ions were encapsulated by the supramolecular ligands, such as porphyrins and macrobicyclics. The supramolecular ligands have been designed and synthesized to provide enough coordination sites for the formation of stable Er(III)-chelated complexes. For getting a higher optical amplification gain, also, the energy levels of the supramolecular ligands were tailored to maintain the effective energy transfer process from supramolecular ligands to erbium(III) ions. Furthermore, to maximize the light-harvesting effect, new aryl ether-functionalized dendrons as photon antennas have been incorporated into lanthanide-cored supramolecular systems. In this paper, molecular design, synthesis and luminescent properties of novel lanthanide-cored integrated supramolecular systems with highly efficient light-harvesting dendritic arrays will be discussed.d.