• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1051-1058
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• 1998

We propose a bandpass filter using wavelength selectivity as variation of writing beam incident angle in photorefractive crystal. From TWM(Two-Wave Mixing) experiment, optimal diffraction properties are induced, and bandpass filter for selection wavelength transmission bandwidth are taken by change of writing beam incident angle.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1305-1312
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• 2000

This paper presents the design and implementation of the CPW end-coupled band-pass filter with the finitely backed conductor (FBC). To reduce the large insertion loss in CPW structure, the improvement in loss characteristic through the change of CPW structure is introduced. The CPW filters with narrow bandwidth are suggested and characterized for their microwave performance using the finitely backed conductor. This structure

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.83-86
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• 2000

가변 필터는 송수신기에서 회로를 간단히 하여 특히 멀티채널을 사용하는 송수신기에서 중추적 역할을 담당하게 된다. 본 논문에서는 소형경량이고, 구조가 단순하여 제작이 간단하며, MMIC화하기 쉬운 실용적인 가변필터를 설계 및 제작하여 그 사용가능성을 제안하였다. 본 논문에서는 중심주파수 1.95GHz, 통과대역이 100MHz인 대역통과 링 필터를 Split 모드 방식으로 구현하고 이를 바탕으로 300MHz의 가변대역폭을 갖는 필터를 제작하였다. 이 필터의 대역폭을 가변하기 위하여 바이어스전압에 따라 커패시턴스가 변화하는 Varactor 다이오드를 사용하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.1909-1913
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• 2008

In this paper, A compact ultra-wideband(UWB) bandpass filter(BPF) with WLAN notched filter has been proposed. H-shared slot is studied and adopted to tighten the coupling of inter-digital capacitor in order to improve the BPF's performance. Three pairs of tapered defected ground structures(DGS) are formed to assign their transmission zeros towards the out of band signal, thereby suppressing the spurious passband. Also Meander line slot is de#eloped to reject the undesired wireless local-area network(WLAN) radio signals. That's combining these three structures we obtain a small sized UWB BPF.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.214-217
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• 2004

In this paper, a Ka-band LTCC (low temperature co-fired ceramic) narrow bandpass filter (BPF) is firstly presented. This BPF shows very narrow 3dB fractional bandwidth of 4.5 ％ centered at 28.7㎓. The advantages of multi-layered LTCC technology such as high integration and vertical stacking capabilities were employed to design three-dimensional interdigital end-coupled embedded microstrip narrow BPF. The difficulties in controlling the precise distance between two adjacent resonators in LTCC end-coupled BPF were overcome by locating the resonators on different layers. The measured insertion loss is 3dB at 28.7㎓, pass band is from 27.9 ㎓ to 29.2 ㎓, and the return loss in the pass band is less than 10 dB.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.800-802
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• 1999

본 논문에서는 기존의 알고리즘에서 벗어나 새로이 제안된 유전자 알고리즘을 이용하여 디지털 필터를 설계하는데 목적이 있다. 이 방법은 아날로그 필터에서 디지털 필터로의 전환이 불필요하며, 기존의 디지털 필터 설계방법과는 달리 저역통과(low-pass), 고역통과(high-pass), 대역통과(band-pass), 대역소거(band-stop) 필터와 같은 주파수 선택별 필터를 각각 독립적으로 설계 가능하게 하고, 이에 따른 계산 손실을 줄일 수 있다. 유전자 알고리즘을 사용하는데 있어 적합도 함수는 주파수 응답 크기를 이용한다. 실제로 주파수 응답특성과 디지털 필터의 계수와는 밀접한 관계가 있으므로, 원하는 필터의 주파수응답특성을 통해, 디지털 필터의 계수를 최적화 한다. 또한 필터계수 최적화 과정에 있어, 선택, 교배, 돌연변이와 같은 유전 연산자 적용시 필터의 계수들은 각각 안정도가 보장되어지는 범위내에서 선택되게 한다. 디지털 필터를 설계한 후 기존의 방법과 새로이 제안된 방법의 성능을 비교 평가 한다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.288-293
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• 2003

In this paper, Filter could use to IMT2000 repeater using resonator of Comb-line form that has waveguide structure and designed. Coupled resonators designed using slot in wall between resonators to compact. 5-stage resonators have equal structure and input and output part was optimized to get into minimum impedance. Band pass filter characteristic satisfied design condition as result that used Chebyshev function that have 0.2 dB ripple and analyze using simulation tool.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.28-35
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• 2010

In this paper, we designed and fabricated a ultra-wideband(UWB) bandpass filter with a good performance of a stopband, and a notched band in passband. The transformed equivalent circuit of the highpass filter was realized by distributed element. A wide-passband with 3-dB fractional bandwidth of more than 100 % was achieved by using optimum response of the HPF. For improving lower and upper stopband characteristic, a cross coupling between feed lines was employed, which was analyzed by desegmentation technique. In order to reject interference of Wireless LAN and Hyper LAN(5.15~5.825 GHz), the narrow notched(rejection) band was realized by a spurline. The fabricated BPF indicated the passband from 3.1 to 10.55 GHz and the flat group delay of less than 0.94 ns over the entire passband except the rejection band. The filter shown sharp attenuation both inside and outside the band and notched band from 5.2 to 6.12 GHz.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.186-189
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• 2000

In this paper, we have designed a bandpass filter to apply the downconverter of the K-band Mu-hung-hwa satellite. To pass only the 25-30% of the bandwidth at the center frequency of 19.6GHz, we have designed a six-order interdigital bandpass filter using microstrip lines. Simulation result of optimization show that insertion loss is -0.275dB and reflection coefficient is -20.95dB at the passband frequency. measurement is determined center frequency, 19.150Hz, insertion loss, -4.1dB, input reflection coefficient. -l5dB and output reflection coefficient -l6dB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.315-318
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• 1999

The purpose of this study is to establish the design theory of a DR ceramic bandpass filter used for WLL basestations and to research on the design theory of bandpass filter. The design procedure is circuit parameters and structural parameters will be derived. It was observed that the filter characteristics at the simulations