• ETRI Journal
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• v.29 no.5
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• pp.676-678
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• 2007

In this letter, we propose a cognitive ultra-wideband radio scheme which is based on a modified chirp waveform. Therefore, it requires only time domain processing in the cognitive radio systems and reduces system complexity and power consumption.

• Journal of IKEEE
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• v.23 no.2
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• pp.395-402
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• 2019

In this paper, we implemented an Ultra-Wideband radar system using Stripmap Synthetic Apertrure Radar algorithm to recognize objects inside a box. Different window functions such as Hanning, Hamming, Kaiser, and Taylor functions to improve image recognition performance are applied and implemented to radar system. The Ultra-Wideband radar system with 3.1~4.8 GHz broadband and UWB antenna were implemented to recognize the conductor plate located inside 1m3 box. To obtain the image, we use the propagation data in the time domain according to the 1m movement distance and use the Range Doppler algorithm. The effect of different window functions to improve the recognition performance of the image are analyzed. From the compared results, we confirmed that the Kaiser window function can obtain a relatively good image.

• Journal of IKEEE
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• v.25 no.1
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• pp.76-82
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• 2021

In this paper, the compressed sensing basic pursuit denoise algorithm adopted to synthetic aperture radar imaging is investigated to improve the object recognition. From the incomplete data sets for image processing, the compressed sensing algorithm had been integrated to recover the data before the conventional back- projection algorithm was involved to obtain the synthetic aperture radar images. This method can lead to the reduction of measurement events while scanning the objects. An ultra-wideband radar scheme using a stripmap synthetic aperture radar algorithm was utilized to detect objects hidden behind the box. The Ultra-Wideband radar system with 3.1~4.8 GHz broadband and UWB antenna were implemented to transmit and receive signal data of two conductive cylinders located inside the paper box. The results confirmed that the images can be reconstructed by using a 30% randomly selected dataset without noticeable distortion compared to the images generated by full data using the conventional back-projection algorithm.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.754-759
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• 2016

A transformer feedback low-noise amplifier (LNA) is implemented in a standard $0.18{\mu}m$ CMOS process, which exploits drain-to-gate transformer feedback technique for wideband input matching and operates across entire 3~5 GHz ultra-wideband (UWB). The proposed LNA achieves power gain above 9.5 dB, input return loss less than 15.0 dB, and noise figure below 4.8 dB, while consuming 8.1 mW from a 1.8-V supply. To the authors' knowledge, drain-to-gate transformer feedback for wideband input matching cascode LNA is the first adopted technique for UWB application.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1290-1297
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• 2019

The paper proposes a distance estimation technique for ultra-wideband (UWB) systems using convolutional neural network (CNN). To estimate the distance from the transmitter and the receiver in the proposed method, 1 dimensional vector consisted of the magnitudes of the received samples is reshaped into a 2 dimensional matrix, and by using this matrix, the distance is estimated through the CNN regressor. The received signal for CNN training is generated by the UWB channel model in the IEEE 802.15.4a, and the CNN model is trained. Next, the received signal for CNN test is generated by filed experiments in indoor environments, and the distance estimation performance is verified. The proposed technique is also compared with the existing threshold based method. According to the results, the proposed CNN based technique is superior to the conventional method and specifically, the proposed method shows 0.6 m root mean square error (RMSE) at distance 10 m while the conventional technique shows much worse 1.6 m RMSE.

• ETRI Journal
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• v.35 no.3
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• pp.397-405
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• 2013

In this paper, two sets of spectrally efficient ultra-wideband (UWB) pulses using zinc and frequency-domain Walsh basis functions are proposed. These signals comply with the Federal Communications Commission (FCC) regulations for UWB indoor communications within the stipulated bandwidth of 3.1 GHz to 10.6 GHz. They also demonstrate high energy spectral efficiency by conforming more closely to the FCC mask than other UWB signals described in the literature. The performance of these pulses under various modulation techniques is discussed in this paper, and the proposed pulses are compared with Gaussian monocycles in terms of spectral efficiency, autocorrelation, crosscorrelation, and bit error rate performance.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.221-224
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• 2005

In this paper, We have designed, fabricated and measured a stacked planar antenna for Ultra-Wideband communication. Radiation parts of the antenna have exponential curve and fed by strip feeding network. We have used the HFSS of Ansoft to simulate the antenna. It was designed to work on a substrate Teflon of thickness 1.575mm and relative permittivity 3.2. The proposed antenna covered the entire UWB band( 3.1GHz $\sim$ 10.6GHz ) for S11$\leq$l0dB. Also the proposed antenna show a good characteristics, linear phase, omni -directional pattern lot UWB applications. Besides the measured results have a reasonable agreement with the simulated results.

• ETRI Journal
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• v.36 no.2
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• pp.309-312
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• 2014

A novel compact pattern diversity slot antenna for ultra-wideband (UWB) and Bluetooth applications is presented. This antenna consists of two modified coplanar waveguides that feed staircase-shaped radiating elements, wherein two different fork-like stubs are placed at the $45{\circ}$ axis. The measured results show that this proposed antenna operates from 2.3 GHz to 12.5 GHz, covering Bluetooth, WLAN, WiMAX, and UWB. The performance of radiation patterns and the corresponding envelope correlation coefficient prove this antenna is suitable for MIMO/diversity systems. Also, the antenna's compact size makes it a good candidate for portable devices.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.33-37
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• 2009

In this paper, a printed small Ultra-Wideband (UWB) antenna with directive radiation characteristics based on combination of electric-magnetic radiators is presented. The combinations of the electric and magnetic type antennas result in the directive radiation patterns for all observed UWB frequency band. Simple combination of dipole antenna and loop antenna is also presented to show that proper configuration of electric radiator and magnetic radiator can produces directive radiation characteristics. The target frequency is from 3.1 GHz to 10.6 GHz with size of $15\;mm{\times}31\;mm$. A proto-type of the combined antenna is simulated, fabricated and measured. Simulation and experimental results of input impedance and gain characteristics of the proposed antenna are presented. There are good agreements between the simulated and measured VSWR curves. Also, the results show the directive radiation characteristics with small antenna form factor over the target frequency range.