• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.465-465
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• 2004

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.209-212
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• 2001

본 논문에서는 Ka-band 위성 중계기용 국부 발진기에 사용하게 될 전압제어 발진기의 EM (Engineering Model)을 비선형 방법으로 설계하였다. 전압제어 발진기의 위상잡음을 개선하기 위하여 공진기로 사용되는 유전체 공진기와 결합하는 마이크로스트립 라인을 high impedance inverter로 구현함으로써 공진회로의 quality factor를 우수하게 유지하여 능동소자에 전달되도록 하였다. 개발된 전압제어 발진기는 0～12V의 제어전압으로 9.7965～9.8032GHz의 발진범위를 갖으며 공급전력은 8V, 17mA을 필요로 한다. 제작된 전압제어 발진기의 위상잡음은 -96.51dB/Hz @10KHz와 -116.5dBc/Hz @100KHz의 특성을 나타내며 출력전력은 7.33dBm을 얻었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.278-283
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• 2004

Due to the complex arrangement of frequency plans and spatial overages in modern satellite communications, channels that are non-contiguous in frequency may be amplified by a single power amplifier and transmitted to the ground through one beam. In this paper, a dual-mode canonical filter with dual-passband is presented. The filter adopts dual-mode technique for mass and volume reduction. Canonical structure is adopted for maximum transmission zero realization. To validate the design technique, a 6-pole dual-mode canonical dual-passband filter for Ka-band(30/20 ㎓) satellite transponder is realized. The measured frequency response of the filter shows good agreement with the computed one.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.3
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• pp.18-27
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• 2000

Signal attenuation of Ka-band satellite communication system due to rain fading is more severe than those of conventional frequency band system, thus an efficient rain fade countermeasure technique is absolutely required. In this paper, we design an improved adaptive modulation system, which switches the modulation mode according to the channel condition, and propose the novel synchronization algorithms. We assume that the modulation scheme is M-ary PSK and the receiver is TDMA burst mode. And the transponder model is the same with KOREASAT-3. By using the adaptive modulation scheme, we satisfy the BER and mean spectral efficiency requirements, simultaneously, which is impossible by using the fixed modulation scheme.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.330-333
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• 2003

본 논문에서는 조립/제작, 시험과정을 통하여 개발된 통신방송위성용 Ka 대역 통신위성 중계기의 구조 및 성능에 대하여 기술한다. 개발된 중계기는 전체 400MHz 대역 내에 100 MHz 대역폭을 갖는 3 개의 통신채널을 수용하여 광대역 멀티미디어 서비스를 지원할 수 있도록 설계되었으며 국내 기술로 제작되어 우주인증을 거친 IFA, RxDC, IMUX, CH-AMP 등의 부품으로 구성되어 있다. 중계기에 대한 성능시험은 EGSE를 이용해 자동으로 수행되었으며, 성능시험결과 대부분의 성능 항목이 요구사항과 부합됨을 확인하였다. 제작된 Ka 대역 중계기에 적용된 위성 중계기 및 부품의 제작 및 시험 기술은 향후 통신해양기상위성에 탑재될 중계기의 개발에 직접 응용이 가능하다.

• Journal of Multimedia Information System
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• v.5 no.3
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• pp.155-162
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• 2018

Nowadays, the tracking technology of Quadrant Detector will become actual by new micro devices. Based on the past filed data of the reception experiment with COMETS satellite, we have studied on new device (AD8302, phase difference detector) was acquired and suspect its abilities. In 1998, we have developed a Quadrant Detector for mobile to track a weak signal from satellite on Ka band of COMETS. The Quadrant Detector is comprised of four dedicated feed components for reception under an environment of Nakagami - Rician fading, and one transmission and reception feed component. We were successful in receiving a 23 GHz beacon signal from ICE transponder of the COMETS and succeeded in tracking the satellite from a moving vehicle at speeds of approximately 10 ~ 20 Km/h on paved roads. In 2018, with new device AD8302, we have verified new QD system and performed a simulation, based on the past filed experiment. This new device shall be improving the tracking abilities from mobile body on the earth to the multimedia satellite.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.621-629
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• 2008

This paper presents a low temperature co-fire ceramics(LTCC) Upconverter for a Ka-band OBS satellite transponder in order for size reduction which is one of the most important requirement for satellite components. A S-band low-pass filter(LPF), a K-band band-pass filter(BPF), and an upconverting MMIC mixer are embedded in the multi-layer structure of the upconverter. All spurious can be selectively rejected by employing a modified Elliptic low pass filter with a multi-pole structure for the S-band LPF. Also an improved performance of out-of-band rejection can be obtained. At the K-band BPF design a layer coupled configuration is employed. The upconverting mixer is an MMIC diode mixer with a double-balanced configuration. Conversion loss and isolation of the upconverter are 9 dB and 51 dBc, respectively. The size of the LTCC upconverter is only $8{\times}7{\times}0.6mm^3$ which is one-third for the thin-film based upconverter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.96-102
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• 2003

The thermal design of MGSE(Mechanical Ground Support Equipment) panel is performed for thermal vacum thest of Ka-band EQM(Engineering Qualification Model) payload of communications and broadcasting satellite. The thermal environments are predicted to evaluate the performance of transponder equipments in the thermal vacum chamber. SINDA is used to verify the thermal design of the heat pipe layout. Embedded 16 heat pipes in the EQM payload developed for Ka-band trasponder equipments are designded properly. The heat fluz loaded on the external facesheet is 265W/㎡ for the hot platear function test of the traspinder equipments, and the zero heat flux for the cold plateau case. The maxium predicted heat transport capability is 2723 W-cm.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.63-70
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• 2006

This paper presents the results of Ka band qualification model multiplexers for COMS Payload to be launched in 2008. These are the input and output multiplexers of the satellite transponder to use available frequency resources effectively and the diplexer of the satellite antenna to use the same reflector for both transmitting and receiving frequency bands, respectively. The input multiplexer with four frequency channels has four(4) independent channel filters which consist of an 8-pole elliptic band-pass filter for high frequency selectivity and a 2-pole equalizer for group delay equalization. For low insertion loss, mass and volume reduction, manifold type os employed for output multiplexer. E-plane T-junction is used for either splitting or combining a frequency band into two sub-bands. Asymmetric inductive irises are used to tune the receiving filter easily. The electrical performance and environmental test such as vibration test, mechanical shock test, thermal vacuum test and EMC test are performed and the results of all qualification model multiplexers are compliant to the requirement of each multiplexer. Followed by this qualification, the flight model equipment will be developed.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.58-58
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• 2004