• 한국전자파학회논문지
• /
• 제23권10호
• /
• pp.1151-1156
• /
• 2012

본 논문에서는 77 GHz 자동차 레이더 시스템에서 거리가 달라도 일정한 감도를 유지할 수 있도록 하는 베이스밴드 필터를 제안하였다. 기존의 DCOC(DC Offset Cancellation) loop 회로를 이용하여 DC offset을 제거함과 동시에 거리에 따른 수신 전력의 크기 차이를 이득으로 상쇄시킬 수 있도록 하였다. 측정 결과, 이득은 최대 51 dB의 크기를 가지며, 고역 통과 차단 주파수는 5 kHz에서 15 kHz까지 가변 가능하게 하였다. 거리에 따른 손실을 보상하기 위한 고역 통과 필터의 기울기는 거리 보상 범위를 위해 -10~-40 dB/decade로 가변이 가능하게 설계되었다. 1 V의 전압에서 전류 소모는 4.3 mA이며, 측정된 NF는 26 dB이고, IIP3는 +4.5 dBm을 가진다. 칩은 65 nm CMOS 공정을 사용하였으며, 입출력 패드를 제외한 크기는 $500{\mu}m{\times}1,050{\mu}m$이다.

• ETRI Journal
• /
• 제41권2호
• /
• pp.262-269
• /
• 2019

This paper introduces a low-cost, high-performance mmWave antenna array module at 77 GHz. Conventional waveguide transitions have been replaced by 3D CPW-microstrip transitions which are much simpler to realize. They are compatible with low-cost substrate fabrication processes, allowing easy integration of ICs in 3D multi-chip modules. An antenna array is designed and implemented using multilayer coupled-fed patch antenna technology. The proposed $16{\times}16$ array antenna has a fractional bandwidth of 8.4% (6.5 GHz) and a 23.6-dBi realized gain at 77 GHz.

• 전자공학회논문지
• /
• 제53권12호
• /
• pp.3-12
• /
• 2016

본 논문은 지뢰탐지용 48채널 배열 UWB 임펄스 레이다 방식의 지면투과레이다 구현과 시험에 대해 기술한다. 지면투과레이더는 기존 금속탐지기의 한계인 비금속 지뢰 탐지의 어려움과 매질 내 금속 성분에 의해 발생하는 높은 오경보 문제점을 극복한다. 본 논문에서는 펄스폭이 600ps 급인 미세한 모노싸이클(Monocycle) 펄스 파형을 사용해, 높은 해상도의 지뢰 전자파 영상을 제공토록 시스템을 구현한다. 특히 신호처리를 통해 지뢰가 매설된 지점을 자동으로 추정하고, 해당 지점에서의 분할된 상세 지뢰 전자파 영상을 사용자에게 제공한다. 기준 성능 분석을 위해 한국 대표 토양인 거친 사양토를 사용한 실내 시험장을 구축하고, 시험장 내의 자동화된 측정 플랫폼에 구현한 레이다를 장착하여 영상 획득 및 탐지심도 분석 등의 시험을 수행한다. 지뢰는 비무장 지대에 매설된 지뢰와 동일한 형태의 모형 지뢰를 사용한다.

• 지구물리와물리탐사
• /
• 제5권3호
• /
• pp.185-192
• /
• 2002

구조물의 안전진단을 위한 비파괴 검사 분야에 사용되는 지표레이다 자료를 정밀하게 영상화시켜줄 수 있는 3 차원 구조보정기법을 살펴보았다. 이 연구에서는 탄성파 자료처리를 위해 개발된 3차원 Kirchhoff 중합전 심도구조보정기법을 이용하여 구조물 안전진단시 중요대상체인 콘크리트 내의 철근, 균열 등을 3차원적으로 영상화시켰다. 철근과 공동대상체가 동시에 존재하는 경우 물성차이의 구분이 가능토록 영상화되었고, 여러 가지 크기의 철근이 존재하는 경우 XX배열법에 의한 영상이 YY배열법보다 더 높은 분해능을 보여주었다. 따라서 보다 정밀한 정보를 얻기 위해서는 일반적인 YY배열 외에 XX배열법의 영상화 결과를 연계하여 분석하는 것이 필요하다. 마지막으로 주향이 교차하는 두 개의 철근이 다른 심도에 존재하는 경우에는 상부의 철근은 정확하게 영상화되나 철근의 높은 전도도로 인하여 하부의 철근은 실제크기보다 좀 더 크게 영상화되는 한계를 보여주었다.

• Journal of electromagnetic engineering and science
• /
• 제10권4호
• /
• pp.309-315
• /
• 2010

A dual-band dual-polarized microstrip antenna array for an advanced multi-function radio function concept (AMRFC) radar application operating at S and X-bands is proposed. Two stacked planar arrays with three different thin substrates (RT/Duroid 5880 substrates with $\varepsilon_r$=2.2 and three different thicknesses of 0.253 mm, 0.508 mm and 0.762 mm) are integrated to provide simultaneous operation at S band (3~3.3 GHz) and X band (9~11 GHz). To allow similar scan ranges for both bands, the S-band elements are selected as perforated patches to enable the placement of the X-band elements within them. Square patches are used as the radiating elements for the X-band. Good agreement exists between the simulated and the measured results. The measured impedance bandwidth (VSWR$\leq$2) of the prototype array reaches 9.5 % and 25 % for the S- and X-bands, respectively. The measured isolation between the two orthogonal polarizations for both bands is better than 15 dB. The measured cross-polarization level is ${\leq}-21$ dB for the S-band and ${\leq}-20$ dB for the X-band.

• Journal of electromagnetic engineering and science
• /
• 제9권3호
• /
• pp.118-123
• /
• 2009

This paper discusses the design and fabrication of a reference signal generator for a naval radar system, including the vibration environment test. The transmit signals of the S-band radar system are synthesized by the reference signal and the phase noise must lower than - 130 dBc/Hz at a 10 kHz offset frequency. To achieve this specification, the phase noise of the reference signal needs to be less than -165 dBc/Hz at a 10 kHz offset. For achieving very low phase noise performance by the reference signal generator, the phase locked loop technique is applied with a 10 Hz loop bandwidth. Also, this reference signal generator has ${\pm}0.35\;ppb$ short-term stability to minimize instant phase errors and high vibration sensitivity against a ship's shaking, unbalanced rotating of antennas and so on.

• 대기
• /
• 제25권1호
• /
• pp.19-30
• /
• 2015

The Ka-band cloud radar (KCR) has been operated by the National Institute of Meteorological Research (NIMR) of Korea Meteorological Administration (KMA) at Boseong National Center for Intensive Observation of severe weather since 2013. Evaluation of data quality is an essential process to further analyze cloud information. In this study, we estimate the measurement error and the sampling uncertainty to evaluate data quality. By using vertically pointing data, the statistical uncertainty is obtained by calculating the standard deviation of each radar parameter. The statistical uncertainties decrease as functions of sampling number. The statistical uncertainties of horizontal and vertical reflectivities are identical (0.28 dB). On the other hand, the statistical uncertainties of Doppler velocity (spectrum width) are 2.2 times (1.6 times) larger at the vertical channel. The reflectivity calibration of KCR is also performed using X-band vertically pointing radar (VertiX) and 2-dimensional video disdrometer (2DVD). Since the monitoring of calibration values is useful to evaluate radar condition, the variation of calibration is monitored for five rain events. The average of calibration bias is 10.77 dBZ and standard deviation is 3.69 dB. Finally, the statistical characteristics of cloud properties have been investigated during two months in autumn using calibrated reflectivity. The percentage of clouds is about 26% and 16% on September to October. However, further analyses are required to derive general characteristics of autumn cloud in Korea.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.609-610
• /
• 2006

A 77GHz MMIC transceiver module consisting of a power amplifier, a low noise amplifier, a drive amplifier, a frequency doubler and a down-mixer has been developed for automotive forward-looking radar sensor. The MMIC chip set was fabricated using $0.15{\mu}m$ gate-length InGaAs/InAlAs/GaAs mHEMT process based on 4-inch substrate. The power amplifier demonstrated a measured small signal gain of over 20dB from $76{\sim}77GHz$ with 15.5dBm output power. The chip size is $2mm{\times}2mm$. The low noise amplifier achieved a gain of 20dB in a band between $76{\sim}77\;GHz$ with an output power of 10dBm. The chip size is $2.2mm{\times}2mm$. The driver amplifier exhibited a gain of 23dB over a $76{\sim}77\;GHz$ band with an output power of 13dBm. The chip size is $2.1mm{\times}2mm$. The frequency doubler achieved an output power of -16dBm at 76.5GHz with a conversion gain of -16dB for an input power of 10dBm and a 38.25GHz input frequency. The chip size is $1.2mm{\times}1.2mm$. The down-mixer demonstrated a measured conversion gain of over -9dB. The chip size is $1.3mm{\times}1.9mm$. The transceiver module achieved an output power of 10dBm in a band between $76{\sim}77GHz$ with a receiver P1dB of -28dBm. The module size is $8{\times}9.5{\times}2.4mm^3$. This MMIC transceiver module is suitable for the 77GHz automotive radar systems and related applications in W-band.

• 한국군사과학기술학회지
• /
• 제22권1호
• /
• pp.1-10
• /
• 2019

In this paper, we propose the track initiation algorithm based on the weighted score for TWS radar tracking. This algorithm utilizes radar velocity information to calculate the probabilistic track score and applies the Non-Maximum-Suppression(NMS) to confirm the targets to track. This approach is understood as a modification of a conventional track initiation algorithm in a probabilistic manner. Also, we additionally apply the weighted Hough transform to compensate a measurement error, and it helps to improve the track detection probability. We designed the simulator in order to demonstrate the performance of the proposed track initiation algorithm. The simulation result show that the proposed algorithm, which reduces about 40 % of a false track probability, is better than the conventional algorithm.

• 한국군사과학기술학회지
• /
• 제26권3호
• /
• pp.246-251
• /
• 2023

RADAR(Radio Detection and Ranging) is an important system for surveillance and reconnaissance by detecting a reflected signal which obtains the range from the radar to the target, and the velocity of the target. The magnitude of the reflected signal varies due to the radar cross section of the target, characteristic of the transmission and reception antenna, distance between the radar and the target, and power and wavelength of the transmitted signal. Thus, the RCS is the important characteristic of the target to determine if the target can be observed by the RADAR system. It is based on the material and shape of the target. We have measured the reflection signal of a simple square-shaped (20 × 20 cm) target made of a new material, a gallium-based liquid metal alloy and compared that of well-known metals including copper, aluminum. The magnitude of reflected signal of the aluminum target was the largest and it was 2.4 times larger than that of the liquid metal target. We also investigated the effect of the shape by measuring reflectance of the F-22 3D model(~1/95 ratio) target covered with/without copper, aluminium, and liquid metal. The largest magnitude of the reflected signal measured from side-view with the copper-covered F-22 model was 2.6 times greater than that of liquid metal. The reflectance study of the liquid metal would be helpful for liquid metal-based frequency selective surface or metamaterials.