• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.788-795
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• 2000

In this paper, a method for the precise impedance measurement of coaxial loads using an offset open and short as the reflection standards and reference air lines with different lengths as the impedance standards is proposed. Measured input impedances of power sensors and thermistor mounts obtained from SWR bridges(5~400MHz) and a vector network analyzer(100~1,000MHz) are presented in the frequency range of 5MHz to 1,000 MHz.

• 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 Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.851-856
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• 2006

This paper studies about design of a transceiver using a single PLL. The transceiver has bandwidth of $424.7\sim424.95MHz$ and the communication method used 21 channels 12.5 KHz channel bandwidth and FSK modulation/demodulation method. Also, we designed low power wireless transceiver for data transmission using a single PLL. Finally, the transceiver set achieves the following characteristics : 8.15dBm output power, 45.97dBc spurious property.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.17-20
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• 2001

In this paper, we realized a transceiver system for short distance communication with a commercial RF module working in ISM band. Also we measured system performance by transmitting baseband data in a building and then we compared the demodulated data bits with stored data bits in a PC connected with demodulator. The RF module In the experiments works only in the bandwidth of 424MHz-429MHz. The signal level degrades as the distance between transmitter and receiver increases. We measured the signal level and bit error and present the measured results with various locations in the building. And it is concluded that the measured data may be used in the design of short distance network in a building.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.343-348
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• 2019

In this paper, a dual-band antenna is proposed for the autonomous vehicle as well as omni-directional. The proposed antenna operates in the 4G/LTE band (1,710~2,170MHz) and 5G/NR band (3,400~3,700MHz). In order to obtain the dual-band operation, the planar monopole antenna is proposed as the novel structure with single port of the 50ohm. To give the properties of dual-band, an additional antenna element with slit was added to the planar monopole antenna, and then a structural adjustment parameter was optimized for achieving the target performance in bands. The planar monopole antenna in the LTE band acts as the coupled feed for the added parasitic radiator in the 5G NR band. The proposed antenna has $38.5{\times}36.0{\times}1.0[mm^3]$ on a ground with diameter of 96mm. From the fabrication and measurement results, the impedance bandwidth (VSWR<2) of the proposed antenna covers 1,480~2,260MHz (LTE band: 1,710~2,170MHz) and 3,310~3,930MHz (5G NR band: 3,400~3,700MHz). The proposed planar monopole antenna also obtained the measured gain and radiation pattern of omni-directional radiation pattern in the anechoic chamber.

• Journal of IKEEE
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• v.16 no.3
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• pp.159-166
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• 2012

In this paper, we designed and implemented the MIMO (Multiple-Input Multiple-Output) antenna for the mobile handset that could be used for multiple services. Simulation results were obtained using SEMCAD X by SPEAG based on the FDTD (Finite Difference Time Domain) Method which showed that S11 values were less than -6 dB (VSWR < 3) for LTE (Long Term Evolution) 700/2300/2500, K-PCS (Korea-Personal Communication Service : 1,750 ~ 1,870 MHz), US-PCS (US-Personal Communication Service : 1,850 ~ 1,990 MHz), Wibro (2,300 ~ 2,390 MHz), Bluetooth (2,400 ~ 2,483 MHz), and US-WiMAX (US-World interoperability for Microwave Access: 2,400 ~ 2,590 MHz) frequency bands. Measured results of the fabricated antenna also showed that it could be used for LTE 700/2300/2500, K-PCS, US-PCS, Wibro, Bluetooth, and US-WiMAX. services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5B
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• pp.639-644
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• 2001

본 논문에서는 저전압(2V) 동작이 가능하도록 high-swing cascode 방식을 이용한 능동소자를 제안하고, 이를 이용하여 400MHz의 차단주파수 특성을 나타내는 저역통과 능동필터를 설계하였다. 제안된 적분기는 이득특성에 영향을 주는 트랜스컨덕스값을 증가시키기 위해 CMOS 상보형 캐스코드 방식을 이용하여 구성되었다. 0.25$\mu\textrm{m}$ CMOS n-well 공정 파라미터를 이용한 Hspice 시뮬레이션 결과, 제안된 적분기는 2V 공급전압하에서 42dB의 이득값과 200MHz의 단위이득주파수 특성을 나타내었다. 또한 이를 이용하여 설계된 저역통과 능동필터는 400MHz의 차단주파수 특성을 나타내고 368MHz에서 416MHz까지 튜닝이 가능하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.5-8
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• 2004

In this paper, a novel 400MHz band small meander microstrip antenna is proposed the shape of the proposed antenna is a waved meander microstrip with a pair rf short pins on th￡ edge. the length of waved meander microstrip is $\lambda_g/4$ but it bends to half its size. Therefore, the total size of the proposed antenna is reduced to about 1/20 which is compared with a square patch antenna the simulated antenna gain is about 3dBi at 424MHz. the proposed antenna of -10dB impedance bandwidth is measured about $1.4\%$.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.83-86
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• 2003

This paper is the research and development including the system design and the prototype system building of the 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.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.193-196
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• 2001

One of the major reasons for not integrating a VCO on one-chip in a PLL (phase locked loop) system is the large chip-to-chip variation of the VCO (voltage controlled oscillator) center frequency. In this thesis, a simple bias technique is proposed to compensate the process fluctuation. The proposed bias technique is applied to the VCO and it reduces the deviation of the VCO center frequency from 35% to 8 %. With the suggested bias technique, a 400 MHz frequency synthesizer is designed for general purpose. It utilizes a programmable divider for various division ratio. The design methodology provides the possibility of the one-chip solution for a PLL system.