• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.5
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• pp.369-375
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• 1996

This paper described the miniaturization of microstrip bandpss filter in UHF using S-plane Prototype. Modern microwave receiver system requires smaller size and better filter performance. The design of filters using bandpass S-plane prototype is made to satisfy these requirements. Bandpass S-plane prototypes are made by exact-synthesis technique using transmission zero locations at wanted frequency bandwidth, and the calculation of prototype values was performed by computer.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.22-28
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• 2007

Spectrum spreading, in its general form, can be conceived as an artificial expansion of the signal bandwidth with respect to the minimum Nyquist band required to transmit the desired information. Spreading can be functional to several objectives, including resilience to interference and jammers and reduction of power spectral density levels. In the paper, signal spreading is manly used for increasing the received energy, thus satisfying link budget constraints, for terminals with low aperture antennas, without increasing the transmitted EIRP. As a matter of fact, in many mobile scenarios, even when MODCOD configurations with very low spectral efficiency (i.e. QPSK-1/4) in DVB-S2 standard, are used, the link budget cannot be closed. Spectrum spreading has been recently proposed as a technique to improve system performance without introducing additional MODCOD configurations under the constraint of fixed power spectrum density level at the transmitter side. To this aim, the design of spectrum spreading techniques shall keep into consideration requirements such as spectrum mask, physical layer performance, link budget, hardware reuse, robustness, complexity, and backward compliance with existing commercial equipments. The proposed implementation allows to fully reuse the standard DVB-S2 circuitry and is inserted as an 'inner layer' in the standard DVB-S2 chain.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.39-44
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• 2021

In this paper, two types of BPF(Band Pass Filter) which are hair-pin and interdigital have been designed for millimeter-wave application using two types of material which are LCP(Liquid Crystal Polymer) and PTFE(Polytetrafluoroethylene) and also, their performances such as bandwidth, insertion loss, and in-band flatness are compared. The proposed BPF are designed as third-order filters, and their pass band is from 26.5 GHz to 27.3 GHz. Interdigital BPF using PTFE substrate has most wide -3 dB S21 bandwidth of 7.8 GHz and hair-pin BPF using LCP substrate has most narrow -3 dB S21 bandwidth among the proposed four BPF. For in-band insertion loss, hair-pin BPF using PTFE substrate achieves low insertion loss better than -0.667 dB, and hair-pin BPF using LCP substrate exhibits relatively high insertion loss among the proposed four BPF better than -0.937 dB. However, the maximum difference in insertion loss performance among the proposed four BPF is 0.27 dB, which is too small to negligible. For in-band flatness, interdigital BPF using PTFE substrate shows greatest performance of 0.017 dB, and hair-pin BPF using LCP substrate exhibits the lowest performance of 0.07 dB. There are tiny difference in in-band flatness performance of 0.053 dB. As a results, it is considered that the BPF using LCP substrate can derive the performances similar to that of the BPF using PTFE substrate in Millimeter-wave band.

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.401-405
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• 2001

We propose a novel channel-switching transmission filter using segmented chirped fiber Bragg gratings (CFBG's) each of which has separate transmission bands in the reflection spectrum of the CFBG. The segmented CFBG's are made by using specially designed slits. The separated reflection spectral bands of the segmented CFBG's are controlled by the attached fiber stretchers, and the controlled reflection bands are used to choose the channels independently. Tunability of the transmission spectra is experimentally demonstrated in WDM transmission experiments.

• Electronics and Telecommunications Trends
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• v.14 no.5 s.59
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• pp.28-33
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• 1999

최근 정보사회에 따른 전파수요가 높아지고 있으며 이에 따른 주파수의 요구가 점차 고주파화되고 있고 미개척분야인 밀리미터파의 개발이 중요한 과제로 대두되고 있다. 본 고에서는 밀리미터파 대역 수동부품용 세라믹 유전체 소재에 관한 동향을 서술하였으며, 이 대역에서 세라믹 소재의 유전특성을 측정, 평가하는 여러 방법 중에서 자유공간법을 이용한 기술에 관하여 소개하고자 한다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.175-181
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• 1999

There are issues regarding how some of traffic parameters should be set so that ATM and non-ATM service parameters can be compatible. For example, policing method used by frame relay based on CIR(committed information rate) will not exactly match the ATM UPC(Usage Parameter Control) method. ATM and the frame relay have different transfer modes and traffic parameters. The cells and frames are police by their own traffic control schemes. For the same information, the real traffic of the ATM side takes greater bandwidth than that of the frame relay side caused by ATM cell format and AAL5 format. IN both networks this bandwidth than that of the frame relay side caused by ATM cell format and AAL5 format. In both networks this bandwidth ratio should be considered on traffic parameter mapping to maintain their QoS and to perform efficient network resource management. In this paper we describe traffic parameter mapping schemes between frame relay and ATM in ATM network and how to expect the bandwidth ratio to maintain FR QoS in ATM network. We assumed frame length distribution to Erlang or Exponential probability density function.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.80-86
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• 2010

This paper describes the development result of S-band Transmitter of STSAT-3 by satellite research center(SaTReC), KAIST. STSAT-3 has two kinds of communication channels, S- band for Telemetry & Command and X-band for mission payload. S-band Transmiiter(STX) consist of modulator, frequency synthesizer, power amp and DC/DC converter. The modulation scheme of STX is FSK(Frequency Shift Keying). The interface between spacecraft OBC and STX is RS-422. The STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under 1E-5. The Test of STX is completed successfully such as functional Test and environmental(vibration, thermal vacuum) Test.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.125-135
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• 2003

In this paper, we developmed and implemented router and bandwidth broker that provides end-to-end QoS in differentiated service IP networks. Our design goal is to provide end-to-end premium service using the EF PHB. The bandwidth broker and router were implemented in the FreeBSD 4.6 platform. For the DiffServ router, we implemented QoS daemon, rollback managment routine, monitoring, and COPS-PR client. Also, Ive implemented bandwith broker which has SLS and resource management function, and signaling protocols for interfacing intra-and inter-domain. On the testbed, we have validated and evaluated the performance of the implemented DiffServ router and bandwidth broker using the inter-domain signaling protocol client in MS Windows platform. The test results show that the end-to-end QoS can be guaranteed for the inter-domain diffServ by the implemented system.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.625-628
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• 1996

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.893-902
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• 2005

We propose a novel single-feed triangular patch antenna with bar-type slots for dual-band circular polarization operation. And also propose a H-type slotted triangular patch antenna to enhance the ratio of the resonance frequencies. 3 cases of desist examples with bar-type slots were investigated and also 4 cases of H-slotted antennas were investigated to meet the dual-band requirement for GPS(Global Positioning System) and DMB(Digital Multimedia Broadcasting). One suitable design example was implemented and measured. Simulation results of the design example for GPS and DMB system show that axial ratio and maximum gain are 3.80 dB, 8.85 dBi for low-band at 1.575 GHz and 2.02 dB, 8.60 dBi for high-band at 2.642 GHz, respectively. Measured results of the implemented antenna show that $S_{11}$ is -12.43 dB for low-band at 1.575 GHz and less than -18.75 dB for high-band, respectively.