• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1229-1235
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• 2003

When finite length image signal is decomposed into 2-band signal and synthesized using 2-band orthogonal wavelet transform, boundary signals are not reconstructed perfectly. To reconstruct them perfectly, the filters which are different from wavelet filter are applied to the boundary signals. Since the existing boundary filters show poor frequency characteristic, the improvement of performance is bounded in practical applications. In this paper, the design method of improvement of frequency characteristic is proposed using inserting a zero to boundary filters which can reconstruct the boundary regions perfectly. Even though the length of proposed boundary filters is shorter, they show 4.2dB∼6.59dB gains in pass band and stop band error power compared with existing boundary filters. But synthesis process is some complicated.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.439-444
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• 2020

In this paper, the analysis of the FSCS (frequency-selected coupling structure) as the coupling coefficient and multi-stage FSCS for enhanced bandstop bandwidth is suggested. The FSCS is composed by the connected coupled-line and open-stub. Basically, the resonance frequency of the FSCS is given by the electrical length of the stub, and the bandwidth is controlled by the coupling coefficient. Multi-stage FSCS is made by addition of another FSCS with the half electrical length. Manufactured bandstop filter using 3 stage FSCS is measured with the stopband of 177.3% and the maximum return loss of 1dB.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.9
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• pp.1033-1038
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• 2015

Complementary Filter is commonly used in signal processing method for real-time position measurement. Butterworth filter characteristic has a uniform gain in the pass band, the blocking band has a good blocking characteristics. Therefore, we propose a method of designing a complementary filter having a characteristic of Butterworth filter characteristic. By setting the appropriate filter coefficients in the simulation it appears to improve the performance of the filter. In the experiment it shows a real-time signal processing is possible by using the calculated filter coefficients in the simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.3
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• pp.25-31
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• 2003

In this paper, we proposed a novel compact microstrip lowpass filter with an ultra-wide stopband and a sharp cutoff frequency response. To improve the cutoff response of the conventional filter, the coupling effect between two open stubs is used. The slot on the ground with conventional shunt open stubs plays an important role of increasing the stopband at a high frequency. The combination of these structures gives the filter the characteristics of an ultra-wide stopband with a prominent cutoff sharpness. The fabricated microstrip lowpass filter with the size of 19.2 mm $\times$ 14.9 mm has -3 dB cutoff frequency at 1.1 GHz and -20 dB stopband from 1.5 GHz to over 30 GHz. The insertion loss is less than -0.15 dB in the passband.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.19-24
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• 2003

A very small size 2.4 GHz ISM band BPF(Band Pass Filter) is realized using LTCC Multi-layer technology. Proposed design method enables to achieve BPF size $2.0\times1.2\times0.8mm^3$. A $lambda/4$ resonator with shunt-to-ground loaded capacitor is used to shorten resonator length, achieving higher quality factor. Also this resonator enables BPF to improve out-of-band rejection. Coupling coefficients between coupled strip-line resonators and external quality factor (Qe) of a resonator are derived and applied to the filter design. The measured results show good agreement with simulated data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.299-302
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• 2008

In this paper, A compact ultra-wideband(UWB) bandpass filter(BPF) with WLAN notched filter has been proposed. H-shaped 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 developed to reject the undesired wireless local-area network(WLAN) radio signals. That's combining these three structures we obtain a small sized UWB BPF.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.91-95
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• 2002

A very small size BPF is realized using LTCC Multilayer technology. A λ/4 resonator with shunt-to-ground loaded capacitor is used to shorten resonator length and achieve higher qualityfactor. Also this resonator enable BPF to improve out-of-band rejection. Coupling coefficients between coupled stripline resonators and external qualityfactor of a resonator are derived and apply to the filter design. The measured results show a good agreement with the simulation.

• 전자공학회논문지 IE
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• v.47 no.2
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• pp.60-65
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• 2010

In this paper, we propose a dual-band filtering method optimized to DBO-CSS systems which are alternatively transmitted in low and high bands. The conventional channel filter which passes entire signal bandwidth causes a problem that excessive noise in neighboring sub-band is added while one of signals in two sub-bands is received. The dual-band filtering proposed in this paper can overcome the performance degradation in the conventional filtering method without increase of hardware complexity. The proposed method is based on two filters to be matched with DBO-CSS signals receiving alternatively and can exclude the undesired noise in neighboring sub-band. Simulation results for the proposed method show better performance about 2.5dB than the conventional one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.5
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• pp.250-257
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• 1985

High order filters are usually realized by cascading second order stages. In this paper, a simple method of pole-zero pairing in the high order band-pass and band-reject filter realization of the elliptic functions is proposed for the enhancement of overall dynamic range. Futrhermore, the optimum sequence of the various biquads of high-pass notch, low-pass notch and symmetrical notch etc., is developed for the elliptic band-pass and band-reject filters.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1267-1268
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• 2015

본 논문에서는 평탄 대역 모드와 손실형 평탄 대역 모드의 투과 스펙트럼을 가지는 PDLS 기반 Lyot형 광섬유 빗살 필터에서 출력되는 편광 상태를 이론적으로 분석하였다. 분석을 위해 파장 가변 레이저, 편광 조절기, 그리고 편광자를 사용하였다. 필터에 배치된 두 개의 반파장판을 적절히 조절하여 평탄 대역 모드와 손실형 평탄 대역 모드를 선택할 수 있다. 편광 조절기를 적절히 조절하면 파장 가변 레이저로부터 나오는 빛의 편광을 원하는 것으로 선택 가능하고 한 채널 내에서 필터의 투과 대역을 미세하게 조절할 수 있다. 그리고 편광자를 통해 출력되는 스펙트럼으로 출력 스펙트럼의 파장별 편광 상태를 알 수 있다.