• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.3
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• pp.44-51
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• 2001

In general, the realization of spaceborne system is constrained by its space environment. In this paper, we suggest chirp stitching technique which generates and processes wideband radar signal with minimum hardware, design and implement transmit/receive equipments and operating programs to satisfy the requirement of this spaceborne high resolution SAR(Synthetic Aperture Radar). We apply the top down design approach to this system, and divide hardware into equipment, module and circuit levels, and software into SR(Software Requirement), AD(Architecture Design), DD(Detailed Design) and coding levels, and then extract each requirement to satisfy the wideband requirement of this spaceborne high resolution SAR. We, at first, test the hardware functions, confirm the wideband handling capability of this system with 85MHz wideband signals generated from two 42.5MHz narrow band signals, and show that this system can be used in spaceborne high resolution SARs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.4
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• pp.359-364
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• 2013

In this paper, we propose a direct sequence ultra wideband (DS-UWB) radar system based on correlation accumulation in the fields of the ship traffic control and the safe ship operation including docking guidance systems. The proposed DS-UWB radar system averages out the noise by accumulating correlator outputs, and thus, provides a reliable distance estimation performance with a shorter estimation time compared with conventional DS-UWB radar systems. From numerical results, it is confirmed that the proposed DS-UWB radar system has not only a shorter average correlation processing time, but also a better distance estimation performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.236-242
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• 2019

Ultra-wideband(UWB) is a technology that can transmit and receive signals at high speeds using a very short signal of wideband of several GHz, and has been recently used in the field of radar technology. Impulse radio(IR)-UWB radar is used in the field of motion recognition with high resolution. In this work, we studied motion recognition using IR-UWB radar. We constructed a development environment to acquire data about motion and implemented a signal processing algorithm for performance enhancement. Based on the signal processing result, the performance was verified through feature extraction and learning of motion.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1175-1184
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• 2008

Delay-sum back projection(DSBP) algorithm and the time reversal algorithm based on the finite-difference time-domain method are compared. The two algorithms, which operate in the time domain, can process the ultra-wideband (UWB) radar data to generate images that are close to the original location and shape of the target. For the experiment, the UWB radar consists of a network analyzer, a resistive V dipole antenna, a scanner, and a control computer. The radar aperture is synthesized by linearly scanning the antenna. A calibration procedure is applied to the measured data to remove signal distortion and clutter. The two algorithms are applied to the same data on the same platform. It is shown that the DSBP algorithm produces better images but takes longer time to produce the images than the FDTD-TR algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.7
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• pp.532-539
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• 2018

A position estimation technique is presented for a missile using high-resolution range profiles obtained by three wideband radars. Radar measures a target range using a reflected signal from the surface of a missile. However, it is difficult to obtain the range between the radar and the origin of the missile. For this reason, the interior angle between the moving missile and tracking radar is calculated, and a compensated range between surface of the missile and its origin is added to the tracking range of the radar. Therefore, position estimation of a missile can be achieved by using three total ranges from each radar to the origin of the missile. To verify the position estimation of the missile, electromagnetic numerical analysis software was used to prove the compensated range according to the flight position. Moreover, a wideband radar operating at 500-MHz bandwidth was applied, and its range profile was used for the position estimation of a missile.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1285-1294
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• 2010

This study describes the design and verification of short range UWB(Ultra Wideband) imaging radar that is able to display high resolution radar image for front area of a UGV(Unmanned Ground Vehicle). This radar can help a UGV to navigate autonomously as it detects and avoids obstacles through foliage. We describe the relationship between bandwidth of transmitting signal and range resolution. A vivaldi antenna is designed and it's radiation pattern and reflection are measured. It is easy to make array antenna because of small size and thin shape. Aperture size of receiving array antenna is determined by azimuth resolution of radar image. The relation of interval of receiving antenna array, image resolution and aliasing of target on a radar image is analyzed. A vector network analyzer is used to obtain the reflected signal and corner reflectors as targets are positioned at grass field. Applicability of the proposed radar to UGV is proved by analysis of image resolution and penetrating capability for grass in the experiment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.899-905
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• 2012

Level Gauge using FMCW Radar is widely used and researched in many areas because of contactless, long range and flexibility. However FMCW level gauge requires wideband RF bandwidth for archiving high resolution of cm grade. In this paper we propose a new tx sawtooth waveform and processing algorithm with narrowband RF for wideband performance. The proposed method is based on STFT(Short-time fourier transform) and single sinusoidal carrier estimation method. From some experiments, we show that the resolution is improved upto 8 times with 300MHz FMCW radar.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.319-325
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• 2011

Recently, collision avoidance systems are under development to reduce the traffic accidents and driver comfort for automotive radar. Pulse radar can detect their range and velocities of moving vehicles using range gate and FFT(Fast Fourier Transform) of the doppler frequency. We designed the real time DSP(Digital Signal Processing) based automotive UWB(Ultra Wideband) radar, and implemented DSP to detect the range and velocity within 100ms for real time system of the automotive UWB radar. We also measured the range and velocity of a moving vehicle using designed automotive UWB radar in a real road environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.208-214
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• 2009

A design and its experimental result of a wideband self-complementary spiral antenna for UWB USPR(Ultrashort-Pulse Radar) system applications is presented. By utilizing the planar-type ultra-wideband microstrip-to-CPS balun, ultra-wideband characteristics of the inherent spiral antenna are retrieved. Also, the design procedure of the spiral antenna is simplified by performing simple impedance matching between separately designed balun and antenna. The proposed spiral antenna is equiangular self-complementary spiral antenna. The implemented antenna demonstrates widebaad performance for frequency ranges from 2.9 to 12 GHz with the relatively flat antenna gain of 2.7 to 5.3 dB and broad beamwidth of more than $70^{\circ}$. From these result, the possibility of a spiral antenna using a ultra-wideband microstrip-CPS balun is verified.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1205-1214
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• 2013

Recently spaceborne SAR systems are increasing image resolution and frequency. As a high quality image resolution, the wider bandwidth is required and a wideband signal generator with RF component is very complicated and RF impairments of device is increased. Therefore, it is very important to improve performance by reducing these errors. In this study, the transmission signal of the wideband signal generator is applied to the phase noise, IQ imbalance, ripple gain, nonlinear model of high power amplifier. And we define possible structures of wideband signal generator and measure the PSLR and ISLR for the performance assesment. Also, we extract error of the amplitude and phase from the waveform and use a quadratic polynomial curve fitting and examine the performance change due to nonlinear device. Finally, we apply a high power amplifier predistortion method for non-linear error compensation. And we confirm that distortion in the output of the amplifier by intermodulation component is decreased by 15 dB.