• 제목/요약/키워드: Aperture Theory

검색결과 63건 처리시간 0.026초

개구면 결합 공진기 급전 마이크로스트립 방향성결합기 해석 및 설계 (Analysis and Design Theory of Aperture-Coupled Cavity-Fed Back-to-Back Microstrip Directional Coupler)

  • 남상호;장국현;남경민;이장환;김철언;김정필
    • 대한전자공학회논문지TC
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    • 제44권3호
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    • pp.7-17
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    • 2007
  • 개구면 결합 공진기 급전 마이크로스트립 방향성결합기의 특성을 해석하였고, 최적 설계를 위한 효율적인 설계 이론을 제시한다. 이러한 목적을 위해 단순하고도 정확한 등가 회로를 도출하였고, 도출된 등가 회로를 바탕으로 결합기의 설계 수식을 유도하였다. 여러 구조적 설계 변수를 결정하기 위해, 유전 알고리즘과 Holder-Mead 방법에 기반한 진화적 이종 최적화 방법을 사용하였으며, 제안한 설계 방식과 최적화 설계 방법의 타당성을 검증하기 위해 10 dB 방향성 결합기를 설계, 제작하였다. 측정된 결합기의 결합 계수는 3 GHz에서 10.3 dB 였고, 반사계수와 isolation은 각각 31.8 dB 와 30.5 dB 였다. 또한 출력단과 결합단 사이에 $90^{\circ}$ 위상 차이를 보였다. 측정치와 설계치의 일치도는 제안한 해석 방법과 등가 회로 및 최적화 설계의 타당성을 검증해 준다.

모스정합을 결합한 UTD에 의한 큰 평행도파관의 고주파간섭 해석 (UTD-Supplemented Mode-matching Method Analysis of High-Frequency Wave Coupling into Large Parallel Plate Waveguides)

  • 권도훈;선영식;명노훈
    • 전자공학회논문지A
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    • 제31A권10호
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    • pp.48-53
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    • 1994
  • The problem of a plane wave impinging upon a semi-infinite paralle-plate waveguide is investigated. The interior fields can be analyzed by converting the initial field into vaveguide modes. Kirchhoff approximation is usually made at the waveguide aperture in the literature. In this paper, a modified approximation is made using the Uniform Gemetrical Theory of Diffraction(UTD). Numerical results show excellent agreement between UTD-supplemented mode-matching solution and UTD solution.

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동축선로로 급전된 원통형 에지-슬롯 안테나의 이론 및 실험 (Theory and Experiment of the Cylindrical Edge-Slot Antenna with Coaxial Line Feed)

  • 유상기;홍재표;조영기
    • 전자공학회논문지A
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    • 제31A권2호
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    • pp.39-44
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    • 1994
  • A theoretical method has been considered for the analysis of a cylindrical edge-slot antenna which belongs to a class of circumferential slot antennas that are suitable for conformal mounting on conducting bodies of revolution. A coupled integral equation is formulated for unknown magnetic currents of both the coaxial aperture and the edge slot, and solved by the moment method. Theoretical values for reflection coefficient obtained based upon the method are compared with our experimental values and other author's results available. There arre good agreement between them.

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Compensation of Equivalent Circuit Model of TE011 Mode Cylindrical Cavity Filter

  • Ryu, Nam-Young;Lee, Jeong-Hae
    • Journal of electromagnetic engineering and science
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    • 제2권2호
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    • pp.100-104
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    • 2002
  • A proper equivalent circuit model for coupling iris has been derived in order to compensate the length of cavity in a $TE_{011}$TEX> mode cylindrical cavity filter. A method to resolve the difference in bandwidth and feature or ripple systematically has been proposed. This method can be applied to other types of waveguide cavity filter.

외부도체면에 축방향 슬롯이 있는 동축선로 도파관의 산란에 대한 특성모드의 해석 : TE의 경우 (Characteristic modes of a longitudinal slot in the outer conductro of coaxial waveguide for scattering : TE case)

  • 윤리호;조영기
    • 전자공학회논문지A
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    • 제32A권7호
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    • pp.23-29
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    • 1995
  • A characteristic mode theory for longitudinal slot of arbitrary width in the outer conductor of coaxial waveguide is applied for calculating the characteristic magnetic currents, the characteristic fields, radiation patterns, and the fields evershere(inside and outside the guide, and in the aperture region). Numerical results of the equivalent magnetic currents and the radiation patterns are compared with those obtained by use of the method of moments.

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PHASE VARIATION IN DOPPLER SIGNAL FOR VARIOUS OPTICAL PARAMETERS

  • Son, Jung-Young;Kim, Myung-Sik;Oh, Myung-Kwan
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1989년도 하계종합학술대회 논문집
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    • pp.629-632
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    • 1989
  • The scattered light intensity from a spherical particle passing through the cross-over region of two coherent laser beams, varies periodically. Photodetection of this light beams produces a periodic signal of varying amplitude. The phase of the signal varies with the particle size and refractive index, the beam crossing angle and wavelength, and the position and size of the scattered ligth collecting aperture. In this paper the phase variation with respect to the particle absorptive index of retraction, collecting lens size and beam crossing angle is calculated using both Mie scattering theory and reflection theory. The two theories show good agreement in phase predictions, especially for large absorptive indices and for small collection lenses. Both theories predict phase to be inversely proportional to the beam crossing angle.

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표면 경계조건을 이용한 코러게이트 혼 안테나 특성 해석 (An analysis of characteristics of corrugated horn antenna using surface impedance condition)

  • 엄만석;박광량
    • 한국통신학회논문지
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    • 제21권6호
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    • pp.1587-1595
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    • 1996
  • We obtained the predicted and measured results for the reflection coefficient and radiation pattern of Ka-band (20- GHz) corrugated horn, which is usually used for feeder of reflector antenna for satellite communication, using suface impedance condition. In order to predict the reture losses of corrugated horn, we analyzed propagation constant of hybrid mode in the corrugated waveguide and then obtained the total reflection coefficient using the circuti theory of multi-step transformer. We also got the radiation pattern of corrugated horn with small flare angle, considering the phase deviation and integrate transverse field on aperture. A test model of corrugated horn antenna for Ka-band designed using theory and program displayed performance and the results agree with the theoretical prediction.

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능동형 SAR 시스템의 송수신 모듈 출력 보정 방법 연구 (A Study of T/R Module Output Compensation Method for Active Synthetic Aperture Radar)

  • 이동우;이종환;김세영;전병태
    • 한국전자파학회논문지
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    • 제21권9호
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    • pp.955-964
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    • 2010
  • 본 논문에서는 기 개발된 능동형 SAR(Synthetic Aperture Radar) 안테나의 송수신 모듈 출력에서 발생하는 이득과 위상 오차를 보정하는 방법에 대해 소개한다. 먼저 오차에 대해 정의하고, 시범 측정을 통해 획득한 측정값을 바탕으로 오차의 특성을 분석한 뒤, 이를 보상하기 위한 송수신 모듈의 제어 방법을 제안하였다. 16조의 송수신 모듈로 구성된 안테나에서 보정 전 이득은 28.2~29.0 dBm, 위상은 $101.7^{\circ}{\sim}165.2^{\circ}$의 분포를 보였으나, 보정후 이득은 27.4~28.0 dBm, 위상은 $116.1^{\circ}{\sim}120.0^{\circ}$의 분포를 나타내었다. 이러한 송수신 모듈의 출력 분포를 바탕으로 배열 이론을 적용하여 안테나 빔 패턴을 생성하고 비교함으로써 제안한 보정 방법이 능동형 SAR 시스템의 성능 만족에 효과적임을 검증하였다.

Research on Digital Complex-Correlator of Synthetic Aperture Radiometer: theory and simulation result

  • Jingye, Yan;Ji, Wu;Yunhua, Zhang;Jiang, Changhong;Tao, Wang;Jianhua, Ren;Jingshan, Jiang
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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    • pp.587-592
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    • 2002
  • A new digital correlator fur an airborne synthetic aperture radiometer was designed in order to replace the conventional analog correlator unit which will become very complicated while the number of channels is increasing. The digital correlator uses digital IQ demodulator instead of the intermediate frequency (IF) phase shifter to make the correlation processing performed digitally at base band instead of analogly at IF. This technique has been applied to the digital receiver in softradio. The down-converted IF signals from each pair of receiver channels become low rate base-band digital signals after under-sampled, Digitally Down-Converted (DDC), decimated and filtered by FIR filters. The digital signals are further processed by two digital multipliers (complex correlation), the products are integrated by the integrators and finally the outputs from the integrators compose of the real part and the imaginary part of a sample of the visibility function. This design is tested by comparing the results from digital correlators and that from analog correlators. They are agreed with each other very well. Due to the fact that the digital correlators are realized with the help of Analog-Digital Converter (ADC) chips and the FPGA technology, the realized volume, mass, power consumption and complexity turned out to be greatly reduced compared with that of the analog correlators. Simulations show that the resolution of ADC has an influence on the synthesized antenna patterns, but this can be neglected if more than 2bit is used.

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Spatial Analysis on Marine Atmosphere Boundary Layer Features of SAR Imagery Using Empirical Mode Decomposition

  • Jo, Young-Heon;Oliveira, Gustavo Henrique;Yan, Xiao-Hai
    • 대한원격탐사학회지
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    • 제33권4호
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    • pp.351-358
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    • 2017
  • A new method to decompose the footprints of marine atmosphere boundary layer (MABL) on Synthetic Aperture Radar (SAR) imagery into characteristic spatial scales is proposed. Using two-dimensional Empirical Mode Decomposition (EMD) we obtain three Intrinsic Mode Functions (IMFs), which mainly present longitudinal rolls, three-dimensional cells and atmospheric gravity waves (AGW). The rolls and cells have spatial scales between 3.0 km and 3.8 km and between 5.3 km and 7.1 km, respectively. Based on previous observations and mixed-layer similarity theory, we estimated MABL's depths that vary from 0.95 km to 1.2 km over the rolls and from 3.0 km to 3.8 km over the cells. The AGW has maximum spectrum at 14.3 km wavelength. The method developed in this work can be used to decompose other satellite imageries into individual features through characteristic spatial scales.