• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.41-47
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• 2007

The first geostationary satellite made by Korea, COMS, has the three different payload ; Meteorological sensor, Oceanographic sensor and Ka-band communication payload. There are Meteorological & Ocean Data Communication Subsystem(MODCS) and Telemetry, Command and Ranging Subsystem(TC&R) as other RF radiation sources. MODCS transmits and receives Meteo and Ocean measurement data from/to earth using L-band and TC&R using S-band. The Ka-band communication payload will provide high-speed multimedia services and communication services for natural disaster such as prediction, prevention, and recovery services in the government communications network.Ka-band beacon is for the earth antenna pointing and the experiment of rain fading. This paper gives the analysis results about the mutual radiation effect on Ka-band communication payload, Ka-band beacon, MODCS and TC&R. Up/Down link power and coupling factor including the geometrical position and distance of antenna, filter rejection and degradation factor due to the different polarization are considered. The results show MODCS and TC&R are compatible for Ka-band communication payload and Ka-band beacon does not interfere with MODCS and TC&R normal operation.

• Information and Communications Magazine
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• v.13 no.8
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• pp.82-92
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• 1996

다양한 형태의 서비스에 대한 수요가 급증하면서 한정된 궤도와 주파수를 이용한 위성통신기술에 대한 효율적인 주파수 활용기술과 새로운 서비스의 개발이 필요하게 되었다. 위성통신시스템의 개발초기에 가장 널리 사용되었던 C대역은 거의 포화상태에 이르렀고, Ku대역도 역시 머지않아 포화상태에 이를 전망이다. 기존의 위성시스템은 주로 방송이나 기업간 사설데이타등의 서비스를 공급해왔는데, 최근에는 개인사용자를 위한 고속 대용량 데이터, 영상, 음성등의 멀티미디어 통신서비스의 공급의 필요가 대두되면서, 광대역통신을 할 수 있는 Ka대역을 이용한 위성통신시스템의 개발이 활발히 진행되고 있다. 서론부에서는 위성통신 주파수의 C대역, Ku대역, Ka대역별 이용현황이 간략히 소개되고, II장에서는 Ka대역의 전파특징에 대하여, III장에서는 Ka대역의 위성시스템 활용기술 및 서비스 발전방향에 관한 각국의 현황을 파악하고, IV장 결론에서는 국내 위성서비스를 위한 연구활동의 발전방향에 관한 의견을 제시하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.640-643
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• 2002

본 연구에서는 위성통신을 이용한 방송 및 멀티미디어 서비스의 확대를 앞두고 20[GHz] 이상의 높은 주파수 대역의 강우에 의한 전파 손실 예측 모델을 제안하고 강우량에 따른 감쇠 정도를 기존의 모델과 비교 분석하였다. 특히 위성 방송대역으로 이용될 Ka 대역에서 강우 감쇠에 의한 전파 손실을 제시하고 Ka 대역 위성통신 링크 설계를 위한 기본 자료를 제공하고 강우 감쇠 극복 대책을 제시하고자 한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.123-129
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• 2023

In this paper, the frequency synthesis(FS) MMIC and the receive MMICs were developed for a Ka-band compact radar. Also a compact Ka-band frequency synthesizer and a receiver were developed based on those MMICs. The FS MMIC and the wireless-receiver(WR) MMIC to receive the baseband frequency were manufactured by a 65 nm CMOS process and the front-end(FE) MMIC to receive the Ka-band frequency was manufactured by a 150 nm GaN process. Linear frequency modulation waveform and pulse waveform for the transmit signal were measured by output signal of frequency synthesizer. The measured performance of developed receiver including the FE MMICs and the WR MMIC were ≧ 80 dB gain, ≦ 6 dB noise figure and ≧ 10 dBm at OP1dB. The measurement results of the developed frequency synthesizer and the receiver including the manufactured MMICs showed that they could be applied to Ka-band compact radar.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.02a
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• pp.159-162
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• 2008

이 연구는 Ka대역 위성방송 서비스를 제공할 때 발생하는 강우감쇠문제를 해결하기 위하여 MPEG-4 SVC 신호를 이용하는 방안에 대하여 고찰하였다. Ka대역 위성방송시스템은 DVB-S2 VCM 모드를 고려하였으며, JSCC (Joint Source Channel Coding) 기법을 이용하여, SVC신호를 Ka대역 위성방송시스템에 적용하였다. SVC신호는 Spatial Scalability, SNR Scalability 및 Temporal Scalability로 구분되어서, PSNR값의 변화에 따른 비트율 변화정도를 분석하였다. 비트율 변화율이 가장 큰 Spatial Scalability를 적용한 SVC신호가 Ka대역 위성방송서비스의 강우감쇠 문제를 해결하기 위한 방안으로 제안되었으며, 이에 대한 분석이 수행되었다.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.48-53
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• 2010

COMS (Communication, Ocean and Meteorological Satellite), which will be launched in June 23rd, 2010 and located on geostationary orbit at the latitude of $128.2^{\circ}E$, is a multi-function satellite for communications, ocean observation, and meteorology. In order to operate Ka-band communication payload effectively, which is one of the three payloads for COMS, the Transponder Monitoring and Control (TMC) system are necessary in ground systems. In this paper, the concepts and design of the TMC system for COMS Ka-band payload are described.

• Journal of Broadcast Engineering
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• v.13 no.6
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• pp.905-914
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• 2008

The paper studied the scheme of applying the MPEG-4 SVC signal to the Ka band satellite broadcasting system through the JSCC system to resolve the rain fading problem generated when providing the Ka band HDTV satellite broadcasting service. The Ka band satellite broadcasting system is based on the VCM mode of the DVB-S2, and the SVC signal is considered as one of the spatial scalability, the SNR scalability and the temporal scalability. The JSCC system jointed all the layers of the source coding system and the channel coding system, and allocated bit rate to source coding and channel coding for each layer to get the optimum receiving quality. The layers are consists of a base layer and an enhancement layer, and the bit rate of each layer is affected by the SVC signal. The applicability of the three SVC signals to the Ka band satellite broadcasting service is analyzed with respect to the rain fading, and the scheme of applying the most excellent SVC to the service is considered.

• Journal of Satellite, Information and Communications
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• v.3 no.2
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• pp.43-47
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• 2008

COMS is the one of Korean hybrid geostationary satellite and is scheduled to be launched in 2009 by Arian V into $128^{\circ}$ E longitude. COMS is designed and manufactured for three main objectives which are Communications, Oceanographic, and Meteorological missions. It provides the weather monitoring, ocean monitoring, and Ka band satellite communication services by means of three different payloads. The Ka band communications payload was developed by Electronics and Telecommunications Research Institute (ETRI), and provides not only the digital transmission for the communication services against natural disaster but also digital transmission for the high speed multimedia services. This paper describes the overview of the electrical and mechanical design and measured performances of the Ka band communications transponder flight model (FM) for COMS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.7
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• pp.1038-1043
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• 2002

The demand for multimedia service using Ka-band satellite communication are growing rapi이y. So, in this paper, we have analyzed rain attenuation with typical model, and proposed prediction model of rain attenuation in high frequency(over 20[GHz]). Path loss model by rain attenuation is based upon rain rate of representative region(6 cities). Proposed prediction model of rain attenuation and parameter of satellite link can be available for the Ka-band satellite communication.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.86-91
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• 2012

This paper described validation results of COMS Ka band antennas beam coverages which were developed by ETRI. After satellite launch, In Orbit Test(IOT) activities are stat to check spacecraft and payloads are still in healthy condition after launch. During IOT phase, ETRI measured radiation patterns of COMS Ka band antennas and compare with ground test(CATR) results. The antenna patterns similarity between IOT results and CATR results show that COMS Ka band antenna withstand launch vibration and in the good healthy condition. After IOT, ETRI performed field test for beam coverage measurements with vehicle to check if Ka band beam coverage are formed well as designed. For the beam coverage measurement, 17 points were selected over the Korean peninsula. The field measurement data were very similar with CATR data and this confirms that beam coverage are formed well over the Korean peninsula as expected.