• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.83-89
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• 2020

A microstrip feedline based open ended folded-slot antenna is proposed for ultra-wideband (UWB) applications. The prototype of the proposed antenna is fabricated on the FR4 dielectric substrate. The proposed antenna has a wide n-shaped slot that is useful for designing circuit components on the same printed circuit board (PCB) as that of the radio frequency (RF) modules. The proposed antenna use two kinds of slots as radiators, and each slots have different characteristics because of the different type of ends of the slot. The wideband characteristic can be obtained by resonances of each slot which are occurred at different frequencies. The measured impedance bandwidth (S₁₁≤ -10 dB) is 2.9-11.56 GHz, and the antenna peak gain is 2-4 dBi over the UWB range. The antenna has a stable omni-directional radiation pattern and only a small group-delay variation across the UWB passband. In addition, we present a modified design with band-notched characteristics of a 5 GHz wireless local area network (WLAN) frequency band.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.751-755
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• 2003

In this paper, We proposed compact multi-layer LTCC (Low Temperature Cofired Ceramic) bandpass filter for Bluetooth module. A ${\lambda}/4$ coupled stripline resonators are designed, which composed of coupled strip-line section and loading capacitance. This resonator with a loading capacitor has slow-wave characteristics. Due to the slow-wave effect of the proposed resonator, it is possible to design and fabricate a compact bandpass filter with a wide upper stop band. Attenuation poles in the lower stop band are achieved using controlling of electro-magnetic coupling between resonators. Using multi-layer LTCC technology, we designed and fabricated band pass filter with a finite attenuation pole and wide upper stopband. The overall size of the filter is $1.2{\times}2.0{\times}1.0mm^3$.

• Publications of The Korean Astronomical Society
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• v.18 no.1
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• pp.51-60
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• 2003

This paper is the research and development including the system design and the prototype system building of the 400MHz wide-band digital autocorrelation spectrometer system for radio astronomy observation, which will be used as back-end signal processing unit of the Dual channel SIS receiver at Taeduk Radio Astronomy Observatory. So in this paper, we performed development of the high speed digitizing sampler, the circular memory buffer, and the correlator module for the 400MHz wide-band digital autocorrelator. This developed system will be use at TRAO after the housing and some calibration.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.10
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• pp.34-40
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• 2001

Ultra Wide Band (UWB) system uses wide band signal, which power spectral density is over all band, It likes as a noise floor, so UWB system can be used without interfering with other communication system. For the first time, we adopted Rayleigh mono pulse antipodal signal which had symmetric characteristic and zero mean. With the power spectral density using stochastic process, we knew that the antipodal signaling scheme removed discrete spectrum and concluded that this had much better spectral suppression, probability of error and data rate than PPM (Pulse Positioning Modulation).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.852-857
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• 2004

In this research, we suggested a new PBG cell with wide stopband. In order to improve the characteristics of the insertion loss, return loss, and ripple, we used two overlapped cells. One is small cell which is made in inside and the other is large cell which is made in outside. The inner cell stops the high band and the outer cell stops the low band. As a result, the new PBG cell had a wide stop band. Insertion loss was about 40dB in stopband and the ripple, and the return loss was improved. Also, the passband is broaden by employing new PBG cells.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.279-287
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• 2002

In this paper, a symmetric microwave lens to steer wide angle and to operate at broad band frequency range for a linear phased array transmitter was designed. To get accurate beam steering performance far a linear phased array transmitter, uniform amplitude transmission characteristics of microwave lens was focused. The measured result for the insertion loss deviation between Input and output ports of microstrip lens with 8 beam ports and 8 array ports was $\pm$3.1 ㏈ over 6~18 ㎓ band, which was very uniform characteristics. Using 8 elements linear array antenna, it was confirmed the radiation beam could be steered over $\pm$60$^{\circ}$ in azimuth. And the measured lens performance data and multi-beam steering pattern were presented.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.203-207
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• 2010

In this paper, The design and implementation of Multi Channel Receiver is described in this paper. This Receiver system operates at X-band with processing received signal, more than 80[dB] dynamic range and wide-band signals at the same time. To process direct received signals, this system has the built-in Digital De-modulators which offer the minimum loss on the receiving signal pass and has high stability by adding Built-In Test (BIT). The performance of Multi Receiver is the following. The gain, noise figure, difference of amplitude and phase on the signal pass is respectively $14{\pm}2[dB]$, 19[dB], ${\pm}2[dB]$, and $10^{\circ}$ below.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.65-70
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• 2004

This paper presents a novel linearization scheme for a nonlinear RF amplifier It is based on the amplitude modulation with envelope signal. The 3rd order distortion generator is composed of two FETs and it adopts a balanced structure for the purpose of main carrier cancellation. The amplitude and phase of the IM3 component can be controlled at RF band. This predistorter is implemented and tested at the KOREA PCS Tx. band (1840∼1870MHz). Experimental results of two-tone test show that the IM3 cancellation is achieved about 30-40 ㏈ for the wide dynamic range. The adjacent channel power ratio is improved by over 10 ㏈ at the broad-band CDMA signal with a peak to average power ratio of l0㏈, and this improvement is maintained through a wide range of output power levels.

• Journal of IKEEE
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• v.17 no.1
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• pp.16-21
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• 2013

Recently, frequency synthesizers are being designed in two ways narrow-band loop or dual-loop for wide-band to reduce the phase noise. However, dual-loop has the disadvantage of center frequency mismatch and requiring an extra loop. In this paper, we propose a new structure that supports a range of 800Mhz ~ 3Ghz with multiple control of the single-loop frequency synthesizer without another loop. The control voltage of the VCO(coarse, fine) will be fixed, and finally the VCO will have a low Kvco. The frequency synthesizer is simulated using UMC $0.11{\mu}m$ process, proposed frequency synthesizer can be used in a variety of applications in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.68-73
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• 2002

This paper presents the implementation of wide-band RFIC amplifier operating from near 50 MHz to 3 GHz using Tachyonics SiGe HBT foundry. Voltage shunt feedback is used for the flat gain and the broad band impedance matching. Initial design parameters are calculated through the low frequency small signal analysis. Since the HBT model was not available at the design time, discrete tuning board was made for fine adjustment in the low frequency range. Fabricated amplifier shows 12 dB gain with 1 dB fluctuation and P1 dB reaches 15 dBm at 850 MHz.