• Title/Summary/Keyword: antenna optics

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High Efficiency Tapered Waveguide Antenna for End-fire Optical Phased Array Device (종단방출형 광위상배열 장치를 위한 고효율 안테나)

  • Byeongchan Park;Nan Ei Yu
    • Korean Journal of Optics and Photonics
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    • v.34 no.6
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    • pp.235-240
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    • 2023
  • The optical signal injected into an end-fire optical phased array propagates along the waveguides inside the device and is emitted from the edge of the antenna. In general, reflection and scattering occur at the boundary, thereby reducing the emission efficiency of the optical signal. In this article, we propose a silicon nitride (Si3N4) tapered waveguide antenna structure whose width is tapered toward the emitting edge, achieving high emission efficiency operating at the 1,550 nm wavelength. The Si3N4 tapered waveguide antenna was numerically designed using the 3D finite-difference time-domain method. The optical signal emission efficiency increased from 78% to 96.3%, while reflectance decreased from 22% to 3.7% compared with the untapered waveguide antenna counterpart. This result will not only boost the optical signal intensity but also mitigate optical noise resulting from back reflection along the waveguide in the end-fire optical phased array device.

Prediction of Antenna Propagation Characteristic in Space Environment Using Ray Tracing Method (광선 추적법을 이용한 우주 환경에서의 안테나 전파 특성 예측)

  • Kim, ChangSeong;Park, Yong Bae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.11
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    • pp.1023-1026
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    • 2016
  • We calculate the propagation characteristic of antennas considering refractive indices of space environments. The effective indices of troposphere, stratosphere, and inonshpere are computed and the ray tracing method, geometrical optics, and Huygens' principle are used to estimate refracted and attenuated electromagnetic wave of space environment.

Numerical Study on the Wireless Communication at 550[nm], 850[nm] and 1550[nm] Wavelength LD in Fog and Pointing Error using Cassegrain Optics (카세그레인 광학계를 사용한 광무선통신 시스템에서 550[nm], 850[nm] 및 1550[nm]의 광 파장에 대한 안개 및 포인팅의 에러의 영향에 대한 해석)

  • Hong, Kwon-Eui
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.12
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    • pp.164-175
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    • 2008
  • Atmospheric effects on laser beam propagation can be broken down into two categories: attenuation of the laser power and fluctuation of laser power due to laser beam deformation. Attenuation consists of scattering of the laser light photons by the fog. Laser beam deformation occurs because of small-scale dynamic changes in the index of refraction of the atmosphere. This causes pointing error. In order to analyse these effect on optical wireless communication system, in this paper uses cassegrain optics as a transmitting and receiving telescope, AID as a detecting device and ill as a light source. The signal modulating and demodulating method is a IM/DD. I show the effects of fog and pointing error and calculate the possible communication distance for BER is $10^{-9}$.

Analysis of a Shaped Dual Offset Reflector Antenna-I : Subreflector Analysis (수정곡면 옵셉 복 반사판 안테나의 복사특성 해석-I : 부반사판 해석)

  • 임규태;이상설
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.9
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    • pp.106-113
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    • 1995
  • The radiation characteristics of the subreflector of a shaped dual offset reflector antenna are analyzed by the uniform theory of diffraction(UTD). The discrete shaped subreflector profile is transformed into an analytic function by the global interpolation. To obtain the first and the second derivative terms on the surface, the local interpolation method is used. The reflection point needed for the geometrical optics(GO) is found by using the multi-dimensional function minimizing algorithm. The radiation pattern of a Gregorian type shaped subreflector is presented. The characteristics of the radiation patterns for various feed edge taperings and frequencies are examined.

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Analysis of Axially Displaced Ellipse Gregorian Dual Reflector Antennas (축이동 그레고리안 이중 반사경 안테나의 해석)

  • 임성빈;최경국;최학근
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.11
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    • pp.1161-1169
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    • 2003
  • In this paper, ADE(Axially Displaced Ellipse) Gregorian dual reflector antennas, which are the special form of Gregorian dual reflector antennas, were analyzed. In the procedure of antenna analysis, the aperture field distribution was obtained by using the geometrical optics and their far-field radiation characteristics were analyzed by using the aperture field method. The analysis results such as antenna efficiency, HPBW(Half Power Beam Width), FNBW(First Null Beam Width), and FSL(First Sidelobe Level) were presented as functions of edge taper and size of main reflector and subreflector. From the results in this paper, we could confirm that ADE reflector antennas have the different radiation characteristics from the classical dual reflector antennas.

Multilayered High-directional Waveguide Grating Antenna Based on Interleaved Etching for Optical Phased Arrays

  • Yang Bo;Qing Wang;Jinyu Wang;Yan, Cai;Wencheng Yue;Shuxiao Wang;Wei Wang;Mingbin Yu
    • Current Optics and Photonics
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    • v.7 no.2
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    • pp.157-165
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    • 2023
  • We propose a highly directional waveguide grating antenna for an optical phased array, achieving high directionality of more than 97% by interleaving the trenches with different etching depths in the silicon nitride layer, and adopting a multilayered structure. Meanwhile, the multilayered structure reduces the perturbation strength, which enables a centimeter-scale radiation length. The beam-steering range is 13.2°, with a wavelength bandwidth of 100 nm. The 1-dB bandwidth of the grating is 305 nm. The multilayered grating structure has a large tolerance to the fabrication variation and is compatible with CMOS fabrication techniques.

Analysis of Cassegrain Dual Offset Reflectors for Compact Payload Test Range (CPTR용 카세그레인 오프셋 복 반사경의 해석)

  • Rho, Sung-Min;Choi, Hak-Keun;Lim, Sung-Bin
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.1
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    • pp.46-53
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    • 2008
  • In general, the cassegrain dual offset reflector is used for the satellite communication antenna, but is analyzed as the reflector system for the CPTR(Compact Payload Test Range) facility in here. The near-field at the test zone of the CPTR is obtained by using the physical optics approximation. The CPTR has to provide a uniform plane wave with the minimum amplitude and phase ripple and the low cross polarization. Therefore, in this paper, the near-field pattern are calculated, and the ripple and taper of the field and the cross polarization are investigated with the variation of the reflector geometry and the position of the test region. Especially, the cross polarization of the antenna axis direction which is not found in the satellite reflector antennas is investigated.

WDM Optical True Time-Delay for X-Band Phased Array Antennas (X-밴드 위상 배열 안테나를 위한 WDM 광 실시간 지연선로)

  • Jung, Byung-Min;Shin, Jong-Dug;Kim, Boo-Gyoun
    • Korean Journal of Optics and Photonics
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    • v.18 no.2
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    • pp.162-166
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    • 2007
  • In this paper, we propose a WDM optical true time-delay (OTTD) beam former for phased way antenna (PAA) systems. It is composed of a delay lines matrix and a multiwavelength source with discrete DFB laser diodes. The building block of a delay lines matrix is a $2\times2$ optical MEMS switch with proper fiber-optic delay line connected between cross ports. A $4\times3$ matrix using four DFB lasers has been fabricated with unit time-delay difference of 12 ps. Maximum time-delay error was measured to be -1.74 ps and +1.14 ps at a radiation angle of $46.05^{\circ}$, corresponding to error range of $-2.87^{\circ}\sim+1.88^{\circ}$. By measuring time-delays at six different RF frequencies from 5- to 10-GHz, we verified the true time-delay characteristic of our OTTD.

A Calculation of the Propagation for Focused Beams Using BPM (BPM을 이용한 안테나 배열의 집속 빔 전파 해석)

  • Kim Jaeheung;Cho Choon Sik;Lee Jae W.
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.5 s.96
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    • pp.465-471
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    • 2005
  • A method of calculation fur propagating and focusing of focused beams generated in antenna arrays, using BPM(Beam Propagation Method), is presented in this paper. Based on the diffraction theory, the beam focusing and Propagation is studied specially for the case of the antenna way fed by the Rotman lens that is able to focus microwave power on its focal arc or generate multiple beams. There are difficulties in performing a full-wave simulation using a commercial EM simulation tool for propagating and focusing of beams because of the structural complexity and the feeding assignment of the antenna array. Therefore, as an alternative solution, the BPM is presented to calculate the beam propagation from the aperture-type antennas. From the point of view of optics, the propagations of the lens have been simplified from the Fresnel diffraction integral to the Fourier transform. Using Fourier Transform, a beam propagation method is developed to show improvement of the resolution by controlling the wavefront of wave Propagating from an aperture-type antenna array. The beam width(or spot size) and the intensity are calculated for a focused beam propagating from an array having $10\lambda$ of its size. For the beams with $20\lambda,\;30\lambda$, and $50\lambda$ of geometrical focal length, the half-power beam widths(or spot size) are about 1.1\lambda,\;1.3\lambda,\;and\;1.9\lambda$ respectively.

Optical true time-delays for phased-array antennas using 2×2 MEMS switches and fiber delay lin (2×2 MEMS 스위치와 광섬유 지연선로를 이용한 위상배열 안테나용 실시간 지연선로)

  • Lee, Gab-Yong;Choi, Yeon-Bong;Shin, Jong-Dug;Kim, Boo-Gyoun
    • Korean Journal of Optics and Photonics
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    • v.13 no.4
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    • pp.289-294
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    • 2002
  • We propose optical true time-delays (TTDs) for phased-array antennas (PAAs) composed of 2${\times}$2 MEMS switches and fiber delay lines, and implement a TTD which shows a maximum scan angle of $120^{o}$ with $30^{o}$ resolution. Since this structure uses only one fixed wavelength laser diode, it provides several advantages such as easy control, high speed operation, and low cost compared with those of the optical TTDs using tunable laser sources. We design a four element linear PAA using the proposed TTDs at 10 ㎓. Simulation results show that the maximum gain is 11.6 dB at the radiation angle $0^{o}$, 11.2 dB at $\pm$$30^{o}$, and 10.6 dB at $\pm$$60^{o}$.