• Journal of electromagnetic engineering and science
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• 제17권3호
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• pp.120-125
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• 2017

A satellite communication (Satcom) antenna mounted on a moving platform provides a controlled heading that enables a geosynchronous satellite to communicate with the ground. A monopulse tracking method is effective for antenna control on a vehicle when it vibrates severely. However, this method has unexpected obstacles and its control performance is insufficient. To improve its control performance, the control command and monopulse error, the signal delay, and the radome effect are evaluated through tests. The authors then propose a method to transform the antenna error from 3D coordinates to 2D antenna coordinates. As a result, the antenna control performance is improved. As indicated in this study, examining antenna systems using the monopulse method on moving platforms is possible by understanding the antenna test process.

• International Journal of Aeronautical and Space Sciences
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• 제17권3호
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• pp.391-400
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• 2016

In satellite operations, stable maneuvering of a satellite's onboard antenna to prevent undesirable vibrations to the satellite body is required for high-quality high-resolution images. For this reason, the onboard antenna's angular rate is typically minimized while still satisfying the system requirement that limits the speed of the onboard antenna. In this study, a simple yet effective method, called the ground station searching method, is proposed to reduce the angular rate of a satellite's onboard antenna. The performance of the proposed method is tested using real flight data from the KOMPSAT-3 satellite. Approximately 83% of arbitrarily selected real flight scenarios from 66 test cases show reductions in the onboard antenna's azimuth angular rates. Additionally, reliable solutions were consistently obtained within a reasonably acceptable computation time while generating an onboard antenna tracking profile. The obtained results indicate that the proposed method can be used in real satellite operations and can reduce the operational loads on a ground operator. Although the current work only considers the KOMPSAT-3 satellite as a test case, the proposed method can be easily modified and applied to other satellites that have similar operational characteristics.

• 한국전자파학회논문지
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• 제23권11호
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• pp.1217-1227
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• 2012

일반적으로 안테나 이득 또는 인자를 측정하는 방법으로서 3-안테나법, 표준안테나법, 표준시험장법 등이 있다. 이들 방법은 주파수 영역에서 반사파 등을 고려하여 자유 공간 또는 준자유 공간의 값을 측정한다. 본 논문은 시간 영역에서 반사파를 추적 제거함으로써 야외시험장에서 자유 공간 안테나 이득 인자를 측정 및 교정하는 방법을 논의한다. 시간 영역에서 측정한 전송 계수 $S_{21}$으로부터 직접파 및 반사파가 수신 안테나에 도달하는 시간차로 이들을 구분하고, 게이팅 기능과 역 푸리에 변환으로 직접파의 주파수 응답 만을 추출하였다. 시간 영역 기능을 갖추고 있는 네트워크 분석기로 안테나 높이를 변화시키면서 이들 파의 경로차를 만들어 1~18 GHz 대역 더블리지 혼 안테나의 반응시간을 분석 하였으며, 그 경로차에 의한 응답을 분리 추출하여 자유 공간 안테나 이득을 측정하였다. 이 결과를ANSI C635의 표준시험장법으로 교정한 결과와 상호 비교하여 좋은 일치가 있음을 보였다.

• ETRI Journal
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• 제40권3호
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• pp.303-308
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• 2018

This paper proposes a simple yet accurate method for estimating the antenna correlation coefficient (ACC) of a high-order multiple-input multiple-output (MIMO) antenna. The conventional method employed to obtain the ACC from three-dimensional radiation patterns is costly and difficult to measure. An alternate method is to use the S-parameters, which can be easily measured using a network analyzer. However, this method assumes that the antennas are highly efficient, and it is therefore not suitable for lossy MIMO antenna arrays. To overcome this limitation, we define and utilize the non-coupled radiation efficiency in the S-parameter-based ACC formula. The accuracy of the proposed method is verified by the simulation results of a 4-port highly coupled lossy MIMO array. Further, the proposed method can be applied to N-port arrays by expanding the calculation matrix.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.145-148
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• 1998

In this paper, a microstrip antenna is designed using a rectangular patch. To find characteristics of the antenna, computer simulations of the rectangular single microstrip patch antenna are performed with changing width. And we compared the result of computer simulation with the experimental value. Through the results, we found that the 3-D FDTD method is an effective method for designing microstrip patch antenna. According to simulation the resonant point has been found it in the frequency received from GPS satellite. It is thought that make it match by adjusting the feedpoint.

• 전기전자학회논문지
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• 제23권3호
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• pp.1100-1103
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• 2019

본 논문에서는 기존의 3차원 구조의 슬리브모노폴 안테나(Sleeve monopole Antenna)를 모노폴과 접지면상의 작은 기생모노폴의 형태로 단순화하여도 비슷한 특성을 보이는 것을 확인하고 PCB상에 보다 광대역인 평면 슬리브모노폴 안테나의 설계 방법에 대해 다룬다. 설계 및 제작된 슬리브안테나는 평면형으로 메인 모노폴과 이에 근접하는 작은 사각형 슬리브로 구성되고 기존의 3차원 슬리브안테나와 비슷한 전방향(omni-directional)특성과 기존보다 46% 더 넓은 대역폭을 나타내었다.

• International Journal of Aeronautical and Space Sciences
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• 제2권1호
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• pp.44-54
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• 2001

This paper describes the antenna alignment method of the tracking antenna system for LEO satellite. The purpose of the antenna alignment is to reduce the angular error due to the structural alignment and the monopulse null point alignment error. The angular error of 3 axis tracking system is the key performance parameter that should be minimized to accurately track satellite movement. The angular error is analyzed via a simulation and boresight measurement. The simulation is done with formulas to be derived from vector concept for 3-axis movement. The formulas of the structural alignment are verified by comparing the formula result with the field measurement. Also, the angular error due to monopulse null shift is obtained via boresight measurement. Based on the analyzed and measured results, the antenna alignment was performed and was verified via tracking test of operating LEO satellite.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.289-292
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• 2009

In this paper, an optimum design center frequency proposes portable RFID reader antenna that is 920MHz frequency using the Taguchi's Method. Proposed antenna is cut corner of opposite angle and it's structure that have slots in four sides microstrip patch of a perfect square shape. This slot structure can miniaturize microstrip patch antenna and confirmed through an experiment that size of antenna about 18% decreases than structure that slot does not exist. Because compact antenna that have structure of slot changes according to complex design variables, analysis and experimental design for minimization of experiment number of times are required for optimum antenna design. In this research, designed antenna that have optimum structure when introduce and designs table of orthogonal arrays of the Taguchi's Method been experimental design that can minimize analysis and experiment number of times, achieve responsiveness analysis of main elements and analyzes the effect and minimizes design repeat with analysis result. Presented experiment result about antenna special quality that permittivity is 4.4 and manufactures to board of Epoxy 3.2T.

• 한국통신학회논문지
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• 제22권3호
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• pp.532-538
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• 1997

Exactly aclculated antenna factors are requeired for determining EMI levels in an actual radiated emission test. In this paper, the antenna factors of short dipole antennas above the ground plane are calculated theoretically for the antenna with Roberts balun specified ANSI C63.5 regulation. Also treated is a half-wavelength dipole antenna with Roberts balun to compare the antenna factors with those of resonant dipole antenna. In formulationof antenna factors the antenna is treated as the boundary value problem of Maxwells equations and is analyzed by the Galerkins method of moments. The balun is treated using circuit theory based on power transmission mismatch.

• 컴퓨터교육학회논문지
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• 제6권3호
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• pp.47-56
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• 2003

We describe a new method for removing non-linear phased array antenna aberration called "squint" problem. To develop a compensation scheme. theoretical antenna and artificial neural networks were used. The purpose of using the artificial neural networks is to develop an antenna system model that represents the steering function of an actual array. The artificial neural networks are also used to implement an inverse model which when concatenated with the antenna or antenna model will correct the "squint" problem. Combining the actual steering function and the inverse model contained in the artificial neural network, alters the steering command to the antenna so that the antenna will point to the desired position instead of squinting. The use of an artificial neural network provides a method of producing a non-linear system that can correct antenna performance. This paper demonstrates the feasibility of generating an inverse steering algorithm with artificial neural networks.