• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.19-25
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• 2005

This paper describes a synthesis method for a self-equalized dual-passband filter. Compared to conventional dual-passband filter, a self-equalized dual-passband filter can reduce BER(bit error rate) in digital data communications and does not need an external equalizer for group-delay equalization. To validate the synthesis technique, a 10-pole dual-mode dual-passband filter which has two self-equalized 5-pole elliptic response passband is synthesized.

• 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.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.497-500
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• 2003

In this paper, a new filter structure to improve frequency response characteristics in CIC(Cascaded Integrator-Comb) decimation filters is proposed. Conventional filters improve passband characteristics, but they make worse slinging band characteristics. In this paper, we propose a new filter which is called IFOP(Interpolated Fourth-Order Polynomials). By using this proposed filter, passband droop and aliasing band attenuation are simultaneously improved. Since proposed filter needs only one multiplication computation is not much. And overall linear phase characteristics are maintained since the proposed filter is also linear phase. Finally, implementation cost of the proposed filter is compared with those of conventional filters.

• 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.

• 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 Navigation and Port Research
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• v.32 no.6
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• pp.481-487
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• 2008

Ship's wireless LAN was in the limelight as equipment of ease, cost reduction, various func tion al i ty. In the paper, a dual-bandpass filter for wireless LAN has proposed, which was designed by using dual-mode square loop resonator with square patch in compliance with 2.4 GHz and 5 GHz band of wireless LAN. The dual-bandpass filter could be designed by adjusting sizes of one perturbation element and three of reference elements in compliance with the frequency bands of 2.4 GHz and 5.8 GHz, Furthermore, new dual-bandpass filter was also designed by adjusting stopband of using open stubs in compliance with the frequency bands of 2.4 GHz and 5.2 GHz. The measured results for the fabricated dual-bandpass filters agreed well with the simulated ones, and hence, it was confirmed that the proposed design method is valid.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.57-62
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• 2023

This paper proposes a tri-band bandpass filter using dual-mode stepped-impedance resonators (SIRs) with parallel coupled structures. The proposed filter adopts U-shaped SIRs with open stubs and parallel coupled lines (PCLs) that have inter-digital and comb-line shorted ends. Two U-shaped SIRs with open stubs build the first and third passband, and the central PCL resonators build the second passband. Five resonators and coupling structures are theoretically analyzed to derive the scattering parameters of the proposed filter. A novel tri-band bandpass filter is designed and fabricated using the induced scattering parameters. The measured result of the fabricated tri-band bandpass filter shows a good agreement with the simulated one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1421-1432
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• 1994

The optimum design and performance of noncoherent TDL considering the effect of distortions due to the IF bandpasss filters are described. NRZ data and ideal filter is presumed in the simulation. The optimum filter bandwidth is calculated in the sense of minimizing the loop's squaring loss, which is equivalent to minimizing the loop's tracking jitter for a given data rate and data signal-to-noise ratio. As a result, the optimum filter bandwidth depends on the signal-to-noise ratio, and is obtained in the range of about 1-2 times of the data rate.

• Journal of Broadcast Engineering
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• v.3 no.1
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• pp.93-99
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• 1998

본 논문에서는 Ka-밴드 위성통신 송신주파수대역(30.085∼30.885 GHz)의 대역통과 필터를 유도성 fin-line 구조를 이용하여 분석, 설계 및 제작하였다. 도파관내의 공진기들이 전계면에 수직한 금속 fin으로 구성된 구조를 해석하는데 가장 적합한 모드정합법을 사용하여 설계하였다. 제작된 필터는 마이크로파대역 뿐만 아니라 밀리미터파대역의 주파수에서도 우수한 필터특성을 갖는다는 특징을 가지고 있으며, 상업용 도파관을 사용하는 대신에 가격이 저렴하고 가공이 용이한 알루미늄을 사용함으로써 대량생산이 가능하다. 또한 도파관내 금속삽입형태에 의한 대역 통과 필터의 구현이 아닌 유한한 두께를 갖는 포토-에칭된 유전체 기판을 삽입함으로써 제작성의 어려움을 해결하였다. 설계, 제작된 필터의 측정결과 통과대역내에서 1.6dBal만의 삽입손실과 18dB이상의 반사손실을 갖는 응답특성을 얻었으며 이론에 의한 계산치와 측정치와의 비교를 통해 본 논문에서 제안된 설계방법의 타당성을 입증하였다.