• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.806-812
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• 2000

In this paper, we theoretically studied on the large antenna array whose element had wider than one wavelength. And we also verified the adaptedness through the experiments. Using grating lobes, we could make antenna have sharp HPBW. Not only HPBW but also SLL could be controlled by giving optimal space for antenna array. In order to verify this method, we designed 4 horn antenna array and measured the radiation patterns at 9 GHz. Each horn antenna has the dimension of 64.3$\times$82.5$\textrm{mm}^2$ and HPBW of 27$^{\circ}$. The space between antennas is longer than one wavelength so that it may have the grating lobes in visible region. As a result of experiments, we could get HPBW of 4.3$^{\circ}$, 3.3$^{\circ}$ and 1.7$^{\circ}$when giving 2.5λ, 2.7λ and 3.0λ of the spacing respectively. We concluded this could be useful making the antenna with narrow HPBW.

• Proceedings of the Acoustical Society of Korea Conference
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• 1991.06a
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• pp.136-141
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• 1991

초음파 영상 진단기에서 영상의 질을 높이기 위해서는 넓은 범우에서 높은 측 방향 해상도가 요구된다. 측 방향 해상도는 변환기에 의해 발생되는 초음파 빔폭에 의해 좌우되는데 기존의 변환기는 초점 부근에서는 빔폭이 매우 좁으나 집속 범위가 제한되는 단점이 있다. 본 논문에서는 넓은 범위에서 균일한 빔폭을 얻을 수 있는 새로운 형태의 변환기를 제안하고 변환기에 의한 음장 분포를 전산기 모의 실험을 통해 구하였으며 그 결과 초점 부근에서는 빔 폭이 기존의 변환기에 비해 다소 넓어지나 집속 범위가 기존의 변화기에 비해 넓어지는 것을 확인할 수 있었다.

• Journal of the Korean Society for Railway
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• v.18 no.2
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• pp.105-110
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• 2015

This paper presents a $4{\times}1$ beam-forming reader antenna system for a new type of RFID based train position detection technology. The required beamwidth of the reader antenna is analytically expressed for different train speeds. The proposed antenna system consists of four rectangular patch elements and two switching couplers which are designed, without any impedance matching networks, for two different antenna modes. The switching coupler is a rectangular quadrature coupler with Pin diodes connecting its center line and the ground plane. The beamwidth of the antenna when the diodes are off and on is $18^{\circ}$ and $39^{\circ}$, respectively. The proposed antenna system will be used for a real train test in the near future.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.398-401
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• 2002

본 논문은 최근 사용이 증가하고 있는 1㎓ 이상 장해파의 허용 기준안을 정하기 위한 측정에 이용되는 피시험체의 최적 회전 스텝 크기를 결정하고 방사 패턴의 측정 및 결과를 나타내었으며 기가헤르츠 대역의 CISPR 허용기준치와 비교하였다. 실제 피시험체를 측정한 결과, 가장 좁은 3㏈ 빔폭은 수평편파에서 약 18도, 수직편파에 대해 약 20도 정도이다. 최대 방사 방향에서 3㏈ 빔폭의 경우 수평편파에서는 60도이며 수직 편파에 대해서는 50도를 보였고, 적절한 스텝 크기는 40개였다. 또한 CISPR에서 제안한 허용기준치에 측정값이 만족하는 것을 알 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.250-254
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• 2001

본 문에서는 Tschebyscheff 다항식 이론을 이용하여 상대적 전류 분포비가 1:2:2:1이 되도록 마이크로스트립 패치 어레이 안테나(MPAA) 설계 제작하였다. 지향성을 갖는 제안된 안테나는 작고 가벼우며 얇다. 또한 빔폭이 14。 인 어레이 안테나이고, 중심 주파수는 10.2553GHz이다. MPAA는 한 개의 마이크로스트립 패치 안테나(SMA:single microstrip antenna)특성과 비교 분석하였다. 그 결과 MPAA는 SMA보다 보다 좁은 복사 전력 빔폭과 큰 최대 복사 전력 이득을 획득했다. PIN 다이오드를 이용한 위상 변환기를 적용하면 전자적 빔스케닝이 가능하고, 소형 레이더 시스템에 적합하다.

• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.264-273
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• 2015

Improvement of the radiation beam profile of a medical ultrasonic transducer has been researched in this paper. In order to improve the beam profile, a new transducer structure has been devised that includes both a shaded electrode and a multi-focus lens. For a linear sound source, the beam profile was investigated through finite element analysis, and then the optimal design of the devised structure was carried out by considering such performances as sidelobe level, focal range and beamwidth simultaneously. In the process, the optimal dimension of the devised structure was derived by using the ratio of the focal range to the minimum beamwidth as a performance index. As a result, the beam profile has been improved to have a lower sidelobe level at -20.2 dB and a consistent narrow beamwidth from 30 mm to 160 mm depth with the minimum beamwidth at 2.04 mm. Further, a prototype transducer was fabricated to have the devised structure, and its performance was measured and compared with the analysis results to confirm the validity of the devised transducer structure.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.637-642
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• 2020

In this study, the SLB(Sidelobe Blanking)/BLB(Blacklobe Blanking) design of the VHF band radar using the low-frequency band having a relatively larger beam width than the S-band or X-band radar. The antenna of the VHF band has a relatively large beam width, so it is reflected from the side lobe. If the reflected target signal is not processed into sidelobe, the false alarm rate of the radar increases by recognizing it from the main lobe signal. This method of SLB blocking is the elimination of the side lobe signal in the front of the array antenna using the central radiating element of the array antenna, and the blocking of side lobe signal from the antenna rear through BLB receiver block. After completed the radar implementation, The function of blocking of side lobe signals was confirmed through the system unit test by Simulated signal generator. Through this study, it will be used in the implementation of the side-lobe blocking technology of the array antenna for low-frequency band radar with large antenna size and beam width in the future.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.38-43
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• 2017

Many studies about generating images of seabed using active sonar have been carried out but image resolution enhancement is still an important problem. Many methods have been proposed to improve sonar resolution and the approach using narrow beam width is commonly and widely applied to enhance azimuth resolution. Unfortunately, this has technical limitations to reduce the beam width. Therefore, signal processing techniques are essential to achieving higher azimuth resolution when an array with conventional beam width is employed. This paper proposes a new approach that utilizes overlapped beams to obtain higher resolution.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.11
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• pp.45-54
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• 2008

In this paper, we use particle swarm optimization (PSO) to design a randomly excited and randomly spaced linear array with either the lowest side lobe level (SLL) or the narrowest beamwidth. The positions and the excitation amplitudes of the array elements are considered as variables to be controlled. The beam pattern is optimized by controlling the two variables simultaneously and randomly. The best beam patterns are obtained using PSO in the fitness function where performance is improved by the random assignment of weight coefficients to each angular sector of the beam Pattern. The weight coefficients and angles are obtained through several trial runs. Also, an extra term, ${\beta}{\ast}BW$, is added to the fitness function to account for the beamwidth as well as the SLL. Is produces the best result for the beam pattern with either the lowest SLL or the narrowest beamwidth. In the former case, the SLL and beamwidth are about -43dB and $32.2^{\circ}$, respectively, with only 10 elements. In the latter case, the SLL and beamwidth are about -26dB and $24.2^{\circ}$, respectively.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.130-133
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• 2010

본 논문에서는 X-band 절전센서용 마이크로스트립 구형패치 배열 안테나의 설계 방법을 제안 하고자 한다. 제안된 배열 안테나는 송 수신 안테나가 각각 1x2배열로 구성 되었다. 안테나는 CST MWS를 사용하여 시뮬레이션 하였고 FR-4 기판(h=1.0mm, ${\varepsilon}_r$=4.4)을 사용하여 제작하였다. 시뮬레이션 결과는 대역폭이 4%(VSWR${\leq}$2), 이득은 6.3dBi, 빔폭은 약 $60^{\circ}$(El)/$15^{\circ}$(Az)로 예측되었다. 안테나는 시뮬레이션 결과를 바탕으로 제작 되었고 절전센서용 RF 송수신기 회로 뒷면에 설치되어 무반사실에서 방사 특성을 측정하였다. 측정된 결과는 대역폭이 7%(VSWR${\leq}$2), 이득은 4.8dBi, 빔폭은 약 $55^{\circ}$(El)/$15^{\circ}$(Az)로 시뮬레이션 결과와 매우 유사한 결과를 얻었다.