• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.326-332
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• 2017

A switched VCO-based UWB transmitter for 3-5 GHz is implemented using $0.18{\mu}m$ CMOS technology. Using RF switch and timing control of DPGs, the uniform RF power and low power consumption are possible regardless of carrier frequency. And gate control of RF switch enables the undesired side lobe rejection sufficiently. The measured pulse width is tunable from 0.5 to 2 ns. The measured energy efficiency per pulse is 4.08% and the power consumption is 0.6 mW at 10 Mbps without the buffer amplifier.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.186-188
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• 2013

A triple 2-of-3 pulse repetition frequency (PRF) scheme is presented for medium PRF pulsed-Doppler airborne radars, and a real-time method is developed that searches for optimal or sub-optimal PRF sets according to momentary battle situations. The effectiveness of the real-time search method of PRF sets is demonstrated by the experimental results obtained using simulated data.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.1-4
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• 2001

Via terahertz (THz) reflection radar, the characterizations of reflected THz electromagnetic pulses are reported. Quasi-optical techniques are used to efficiently reflect pulses of THz electromagnetic radiation from an aluminum mirror and several conducting and nonconducting materials. An incident THz pulse is reflected up to 9 times to know the magnitude change of a reflected pulse from the aluminum mirror. Using this method, aluminum board, undoped silicon, quartz, and LDPE samples' reflection coefficient and index of refraction can be measured. These results suggest a possible application of transient THz reflection spectroscopy without surface contact.ontact.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.507-513
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• 2002

In this paper, the receiver using Heterodyne type is designed and implemented for a pulse radar at 9.4 GHz. The If amplifier, which occupies a significant size in a Heterodyne receiver for pulse radars, can be removed. Furthermore, by using detector logarithmic video amplifier in baseband, the receiver has a small size and it's characteristic shows a high dynamic range and sensitivity. From the results of measurements, the minimum receiver power of -70 dBm and selectivity of 55 dB are obtained.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.453-460
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• 2010

For high quality image acquisition, compensating air-vehicle motion is essential for airborne SAR system. This paper describes a timing control based motion compensation method for airborne SAR system. Efficient timing control is critical for SAR system since it maintains many timing signals and timing setting for the signals should be updated frequently. This paper proposes Timing Cluster method as an efficient means for timing control of SAR system. Moreover, this paper suggests a simple and efficient method to compensate air-vehicle motion based on the Timing Cluster method. Timing Cluster method enables SAR system to control the timing in a timing noncritical way just maintaining little amount of information.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.171-181
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• 2013

Recently, ground penetrating radar(GPR) has been widely used in detecting metallic and nonmetallic buried landmines and a number of related researches have been reported. A novel preprocessing method is proposed in this paper to flag potential locations of buried mine-like objects from GPR array measurements. GPR operates by measuring the reflection of an electromagnetic pulse from discontinuities in subsurface dielectric properties. As the GPR pulse propagates in the geologic medium, it suffers nonlinear attenuation as the result of absorption and dispersion, besides spherical divergence. In the proposed algorithm, a logarithmic transformed regression model which successfully represents the time-varying signal amplitude of the GPR data is estimated at first. Then, background signals may be densely distributed near the regression model and candidate signals of targets may be far away from the regression model in the time-amplitude space. Based on the observation, GPR signals are decomposed into candidate signals of targets and background signals using residuals computed from the estimated value by regression and the measurement of GPR. Candidate signals which may contain target signals and noise signals need to be refined. Finally, targets are detected through the refinement of candidate signals based on geometric signatures of mine-like objects. Our algorithm is evaluated using real GPR data obtained from indoor controlled environment and the experimental results demonstrate remarkable performance of our mine-like object detection method.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.455-455
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• 2006

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.306-308
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• 2005

The vehicle detection method using pulse radar has the advantage of maintenance in comparison with loop detection method. We have the information about the vehicle being and position by dividing the signals into sectors in accordance with SSC method, and by applying the discriminant function based on stochastical data. We also reduce the signal processing time.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.397-400
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• 2006

본 논문에서는 DSP를 이용하여 코히어런트 레이더에 사용될 수 있는 확장성이 용이한 디지털 펄스 압축기를 시간영역에서 설계하고 그 내용을 분석하였다. 수신 거리 셀 및 FIR 필터 탭(tap) 수에 따른 펄스압축 연산시간을 ADSP21060을 사용하여서 분석함으로써, 설계하고자하는 레이더 시스템 요구 파라미터 들이 정해지는 경우 펄스압축기 구성에 소요되는 DSP의 수행 기능과 소요 수를 쉽게 예측할 수 있도록 운용특성을 분석하였다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.91-96
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• 2005

In this paper, describes the design and performance of a 1.5 kW solid-state pulsed power amplifier, operating over 2.7-2.9 GHz at a duty of 10% and with a pulse width of 100 us for radar application. The solid-state pulsed power amplifier configures a series of 8-stage cascaded power amplifier with different RF output power levels. Low loss Wilkinson combiners are used to combine output powers of six 300W high power solid state modules. Tests show peak output power of 1.61 kW, corresponding to PAE of 26.2% over 2.7-2.9 GHz with pulse width of 100 us and a PRF of 1 kHz.