• Title/Summary/Keyword: Rectangular Aperture

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Analysis of Rectangular DRA(Dielectric Resonator Antenna) using Dielectric Waveguide Model) (유전체 도파관 모델을 이용한 육면체 공진기 안테나 분석)

  • 최원규;이범선
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.5
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    • pp.755-762
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    • 2000
  • In this work, we present the resonant frequencies, Qrad, and impedance bandwidth of rectangular dielectric resonator antenna(DRA)for a broad range of aspect ratios using Dielectric Waveguide Model. These presented data are compared with simulation and measurement. The DRA having relative permittivities of 37.84 and 90 have been fed by a coaxial cable and fed using a aperture-coupled method for comparisions. The approximate resonant frequencies are shown to have the prediction error of about 8% and impedance bandwidth is found to have large prediction variation according to feeding method. The data presented in this paper can be used when the aspect ratios of DRA have to be determined for a given resonant frequency and impedance bandwidth.

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Forced Convection Heat Transfer from an Inner Surface of a Two-Dimensional Rectangular Cavity (이차원 사각형 공동 내부에서의 강제 대류 열전달)

  • Seo, T.B.;Han, K.Y.;Kange, Y.H.
    • Journal of the Korean Solar Energy Society
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    • v.22 no.4
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    • pp.77-84
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    • 2002
  • In order to investigate forced convection heat transfer due to the wind from the inner surface of a cavity receiver for a parabolic dish type solar energy collecting system, a two-dimensional rectangular cavity receiver is prepared and installed in a wind tunnel. The convection heat transfer coefficient of the inner surface of the receiver is dependent on the direction and the velocity of the wind. The attack angle of the cavity and the air velocity in the tunnel are controlled in a wide range so that the effects of the attack angle and the wind velocity on the heat transfer coefficient can be studied. The skirt is installed at the aperture of the cavity in order to reduce convective heat loss. The effects of the length and the installation angle of the skirt on convection heat transfer of the cavity are tested. It is found that convection heat loss can be significantly reduced by installing the skirt. Also, it is known that heat transfer from the cavity can be minimized if the angle of the skirt is $90^{\circ}$ to the outer surface of the cavity.

Circular Dual Mode Horn Antenna(CDMHA) with Modified Aperture to Improve E/H-Plane Radiation Pattern Symmetry (E/H 평면 방사 패턴 대칭성 향상을 위해 개구면이 변형된 원형 이중 모드 혼 안테나)

  • Kim, Jae Sik;Yoon, Ji Hwan;Yoon, Young Joong;Lee, Woo-Sang;So, Joon-Ho
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.5
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    • pp.502-507
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    • 2013
  • In this paper, a circular dual mode horn with modified aperture is proposed to improve a E/H-plane radiation pattern symmetry of a conventional oversized circular dual mode horn. The proposed antenna consists of a feeding section, a mode generation section and a phase matching section which has aperture shape transition from circle to ellipse or rectangle to improve a E/H-plane radiation pattern symmetry. To compare the performances between the proposed antenna and the convenional circular dual mode horn, the conventional circular dual mode horn and the proposed circular dual mode horn with rectangular aperture are fabricated and researched at 15 GHz. The measured results show that the conventional circular dual mode horn has 3.394 dB difference while the proposed antenna has only 0.539 dB difference between E and H-plane radiation patterns within the -11 dB beamwidth($53^{\circ}$) which is required beamwidth of the feed horn for the maximum aperture efficiency where f/d ratio of reflector antenna is 1.

Design and Fabrication of Dual Linear Polarization Patch Antenna with Aperture Coupled Feeding Structure (개구 결합 급전 구조를 갖는 이중 선형편파 패치 안테나의 설계 및 제작)

  • Joong-Han Yoon
    • The Journal of the Korea institute of electronic communication sciences
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    • v.18 no.6
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    • pp.1015-1022
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    • 2023
  • In this paper, we propose DLP(Dual Linear Polarization) antenna with aperture coupled feeding structure for private network. The proposed antenna has general aperture coupled structure and design two port between top and bottom layer to obtain the enhanced isolation. Also, The size of each substrate(top and bottom layer) is 34.0 mm(W)×34.0 mm(L), which is designed on the FR-4 substrate which thickness (h) is 1.0 mm, and the dielectric constant is 4.4. Also, the size of patch antenna is 12.70 mm(W2)×14.60 mm(L3), and it is located on the top layer. The size of feeding line is 24.0 mm(W2)×1.6 mm(L3), and is located at the bottom layer Also, rectangular slot is located on the ground plane between top layer and bottom layer. From the fabrication and measurement results, bandwidths of 300 MHz (4.52 to 4.82 GHz) for feeding port 1, and 170 MHz (4.65 to 4.82 GHz) for feeding port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is got under the -30 dB. Also, cross polarization isolation between each feeding port obtained

CONSTRUCTION OF 21CM COSMIC RADIO ANTENNA (21CM 우주전파 수신용 안테나의 제작)

  • Park, Jong-Ae;Yang, Jong-Man;Han, Seok-Tae;Park, Yong-Seon
    • Publications of The Korean Astronomical Society
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    • v.8 no.1
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    • pp.1-15
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    • 1993
  • We made a pyramidal horn antenna system for 21cm cosmic radio wave. The antenna system has a rectangular waveguide with $TE_{10}$ mode and a copper probe to detect the electromagnetic wave in waveguide. The parameters of the probe are obtained by experiments using two waveguides. Pyramidal horn antenna is designed to get a gain of 20dB. The size of the aperture of this horn is $94cm{\times}74cm$. The beam width of half power is about $14.7^{\circ}$ for the frequency of 1.4GHz. The horn is made of aluminum plate with a thickness of 2mm. The signal from horn and waveguide is amplified in a receiver system and is converted into DC in the detecter. The intensity of the signal is recorded on a chart recorder. We observed the sun using this simple radio telescope and obtained the brightness temperature of $2.2{\times}10^5K$, which indicates that the sun is quiet at 21cm.

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Lowpass Filter Design For Eliminate The Harmonic Signals Using Photonic Bandgap Structure

  • Kim Jang Kwon;Kim Dong Sik;Kang Chang Soo
    • Proceedings of the IEEK Conference
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    • summer
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    • pp.19-22
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    • 2004
  • The goal of this study is to realize the PBG lowpass filter using novel PBG structure modification both upper layer and ground layer. It has been designed three aperture slots of ground layer for PBG structure which the center slot shape of ground is two type, rectangular and dumbbell. This PBG LPF has the character of the broader stopband and smaller size than typical LPF. The measurement results have matched the simulated ones. It has the cutoff frequency of each 4.465GHz and 3.52GHz and at least -20dB of the signal suppression at the stopband

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Fabrication and Characterization of Miniaturized HTS Microstrip Antennas Using "H"-type Resonator (H 형태 공진기를 이용한 소형화된 HTS 안테나의 제작 및 특성 해석)

  • 정동철;윤창훈;황종선;최창주
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.7
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    • pp.282-287
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    • 2003
  • ″H″ type resonator has the advantage for the miniaturization of high-T7 superconducting (HTS) microstrip antenna in comparison with the conventional microstrip antenna such as rectangular type or circular type. In this paper we designed miniaturized HTS antennas using this "H"-type resonator and reported the characteristics of our antennas including return loss, bandwidth, radiation patterns, efficiency and so on. To fabricate the "H" type antenna, HTS YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) thin films were deposited on MgO substrates using rf-magnetron sputtering. For comparison between normal conducting antennas and superconducting antennas, the gold antennas with the same dimension were also fabricated. An aperture coupling was used for impedance matching between 50 $\Omega$ feed line and HTS radiating patch. The ″H" type superconducting antenna showed the performance of 1.38 in SWR, 26 % in efficiency, and 13.8 dB in the return loss superior to the normal conducting counterpart.

Fast Measurement of Eyebox and Field of View (FOV) of Virtual and Augmented Reality Devices Using the Ray Trajectories Extending from Positions on Virtual Image

  • Hong, Hyungki
    • Current Optics and Photonics
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    • v.4 no.4
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    • pp.336-344
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    • 2020
  • Exact optical characterization of virtual and augmented reality devices using conventional luminance measuring methods is a time-consuming process. A new measurement method is proposed to estimate in a relatively short time the boundary of ray trajectories emitting from a specific position on a virtual images. It is assumed that the virtual image can be modeled to be formed in front of one's eyes and seen through some optical aperture (field stop) that limits the field of view. Circular and rectangular shaped virtual images were investigated. From the estimated ray boundary, optical characteristics, such as the viewing direction and three dimensional range inside which a eye can observe the specified positions of the virtual image, were derived. The proposed method can provide useful data for avoiding the unnecessary measurements required for the previously reported method. Therefore, this method can be complementary to the previously reported method for reducing the whole measurement time of optical characteristics.

Fabrication of Master for a Spiral Pattern in the Order of 50nm (50nm급 불연속 나선형 패턴의 마스터 제작)

  • Oh, Seung-Hun;Choi, Doo-Sun;Je, Tae-Jin;Jeong, Myung-Yung;Yoo, Yeong-Eun
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.4
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    • pp.134-139
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    • 2008
  • A spirally arrayed nano-pattern is designed as a model pattern for the next generation optical storage media. The pattern consists off types of embossed rectangular dot, which are 50nm, 100nm, 150nm and 200nm in length and 50nm in width. The height of the dot is designed to be 50nm. The pitch of the spiral track of the pattern is 100nm. A ER(Electron resist) master for this pattern is fabricated by e-beam lithography process. The ER is first spin-coated to be 50nm thick on a Si wafer and then the model pattern is written on the coated ER layer by e-beam. After developing this pattern written wafer in the solution, a ER pattern master is fabricated. The most conventional e-beam machine can write patterns in orthogonal way, so we made our own pattern generator which can write the pattern in circular or spiral way. This program generates the patterns to be compatible with the e-beam machine from Raith(Raith 150). To fabricate 50nm pattern master precisely, a series of experiments were done including the design compensation for the pattern size, optimization of the dose, acceleration voltage, aperture size and developing. Through these experiments, we conclude that the higher accelerating voltages and smaller aperture size are better for mastering the nano pattern which is in order of 50nm. With the optimized e-beam lithography process, a spiral arrayed 50nm pattern master adopting PMMA resist was fabricated to have dimensional accuracy over 95% compared to the designed. Using this pattern master, a metal pattern stamp will be fabricated by Ni electro plating for injection molding of the patterned plastic substrate.

Numerical reconstruction of Incoherent Holography using the triangular interferometer (삼각형 간섭계를 이용한 Incoherent 홀로그래피의 수치적 재생에 관한 연구)

  • Bae, You-Seok;Lee, Hyuk
    • Proceedings of the KIEE Conference
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    • 1994.11a
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    • pp.388-390
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    • 1994
  • We are familiar with the holography in these days. For making holography the coherent sources like LASER are used in many fields. But coherent holography has many problems. Coherent holography needs many instrument for practical use like 3-D TV case. In solving the problem we use the non-coherent source. Nowadays many methods like conoscopic holo graphy using anisotropic crystal, shadow casting and interferometric systems are suggested. In this paper we make the hologram using the triangular interferometric systems. [1],[2],[3],[4]. We explain the afocal and double-afocal system which consists of the triangular interferometric system. The holography made in one point and two point cases is imaged on CCD camera and we handle the image data digitally for the reconstruction efficiently. In reconstructing the hologram the Fraunhofer diffraction theory is used. We adopt the rectangular aperture for the convenience of calculation. In the future we must reconstruct the perfect 3-Dimensional object by optical method. For this, we have many problems like resolution problem. We must solve these problem for perfect reconstruction.

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