• 한국초전도학회:학술대회논문집
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• v.10
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• pp.193-196
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• 2000

A new type low-pass filter design method based on a coupled line and transmission line theory is proposed to suppress harmonics by attenuation poles in the stop band. The design formula are derived using the equivalent circuit of a coupled transmission line. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range and low insertion loss. The seventh-order low-pass filter designed by present method has a cutoff frequency of 0.9 CHz with a 0.01 dB ripple level. The coupled line type low-pass filter with strip line configuration was fabricated by using a high-temperature superconducting (HTS : YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin film on MgO(100) substrate. Since the HTS coupled tine type low-pass filter was proposed with five attenuation poles in stop band such as 1.8, 2.5, 4, 5.5, 6.2 GHz. The fabricated low-pass filter has improved the attenuation characteristics up to seven times of the cutoff frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.6
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• pp.317-326
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• 1985

A broad-band design method of a lumped-element 3dB quadrature hybrid without magnetic coupling is proposed and discussed, where techniques of cascading fundamental hybrids via second-order delay equalizers and adding matching sections are adopted. It is shown that the designed broad-band lumped-element 3dB quadrature hybrid can be easily constructed and its bandwidth reaches up to 54%. Furthermore, the esperiments have been carried out, the results of which agree with the theoretical ones, and hence, the validity of the broad-band design method proposed here was confirmed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.2
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• pp.128-132
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• 2015

In this paper, a microstrip dual mode band pass filter with doubly fed line is proposed. The proposed filter consists of a corner truncated patch with right crossed slots and doubly fed lines. In general, the resonator with the right crossed slots simultaneously has size reduction and spurious response suppression. In order to improve the rejection performance in out of its higher stop band, the dual mode resonator is excited by using doubly fed line. Details of the filter characteristics are described, and both simulated and measured results of the designed filter are presented.

• ETRI Journal
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• v.46 no.2
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• pp.218-226
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• 2024

This paper presents a novel circular fractal ring monopole antenna for ultra-wideband (UWB) hardware with dual band-notched properties. The proposed antenna consists of four crescent-shaped nested rings, a tapered feeding line at the front of the dielectric material, and a semicircular ground plane on the backside. In this design, the nested rings are used both as a radiation element and a band rejection element. The proposed antenna has a bandwidth of 9.03 GHz, which works efficiently in the range of 2.63 GHz-11.66 GHz with the dual notched bands of Worldwide Interoperability for Microwave Access (WiMAX) at 3.15 GHz-3.66 GHz and wireless local area network (WLAN) at 4.9 GHz-5.9 GHz, respectively. The antenna has a compact size of 20 mm × 30 mm × 1 mm (0.177 × 0.265 × 0.0084 λ0) and is implemented using a flame-retardant type 4 (FR4) material. It has a maximum gain of approximately 4 dB in its operating range, and experimental results support the simulation predictions with high accuracy. The findings of this study imply that the designed antenna can be utilized in UWB applications.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.363-363
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.333-334
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.142-143
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• 2003

EDFA의 이득(gain)과 잡음지수(noise figure)는 매우 중요한 특성 중의 하나이다. 전송 시스템에서 필연적으로 발생하는 ASE 잡음을 제거하는 것이 중요하다. EDFA의 중간에 필터(filter)와 아이솔레이터(isolator)를 삽입하여 불필요한 ASE를 제거함으로써 이득과 잡음지수를 향상시킬 수 있으며, 기존의 단일경로(single-pass) EDFA에서 필터의 위치가 40-60％ 근처에서 이득과 잡음지수 향상이 가장 크게 된다. 그러나, 거울(mirror)을 사용하여 증폭 효율을 높인 이중경로(double-pass) EDFA에서 필터에 의한 이득 향상에 관한 연구발표는 아직까지 없다. (중략)

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.652-656
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• 2011

In this paper, a transmitter-based multipath processing and inter-channel interference (ICI) cancellation scheme for a ultra-wideband (UWB) spatial multiplexing (SM) multiple input multiple output (MIMO) system is presented. It consists of taps delayed lines and zero-forcing (ZF) filters in the transmitter and correlators in the receiver. For a UWB SM MIMO system with N transmit antennas, M receive antennas, and Q resolvable multipath components, the BER performance of a linear transmit ZF scheme is analyzed in a log-normal fading channel and also compared with that of a receiver-based ICI rejection approach. It is found that when M ${\leq}$ N, the transmit ZF processing approach outperforms the ZF receiver while making the mobile units low-cost and low-power.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2733-2736
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• 2003

This paper proposes a dry-type active surface EMG electrode for the myoelectric prosthetic hand. The designed electrode is small size for embedding in the socket of prosthetic hand, and it has three leads including the reference of signal. To acquire EMG signal rejected the power noise, a precision differential amplifier and various filters such as the band pass filter band rejection filter, low pass and high pass filter are embedded on the electrode. The final output of the electrode is integrated absolute EMG (IEMG) obtained by full rectifier and moving average circuits. From experimental results using the implemented dry-type active surface EMG electrode, the proposed electrode is feasible for the myoelectric prosthetic hand.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1564-1568
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• 1987

A design methodology for front ends of a Direct Broadcasting satellite (DBS) Receiver for X-band was reported by utilizing Monolithic Microwave Integrated Circuits (MMIC) technology. The frequency converter including a three-stage low-noise amplifier, a image frequency rejection filter, and a mixer and buffer amplifier was designed by a Home-made CAD program. The results of computer simulation using the CAD program showed that overall gain was over 36.63dB, and noise figure below 2.55dB, respectively.