• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.338-342
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• 2003

본 논문에서는 개방 스터브(open stub)와 전송선로가 커플된(coupled) 구조를 Chebyshev prototype을 이용하여 저역통과 여파기를 설계하였다. 같은 길이의 스터브를 연속적으로 배열함으로써 깊은 저지대역을 갖고, 커플링에 의해 우수한 스컷 (skirt) 특성을 갖는 여파기를 설계할 수 있었다. 또한, 감쇄극이 다른 스터브를 추가로 연결하여 저지대역을 확장하였다.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.387-392
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• 2014

In this paper, a size-reduced Wilkinson balun with wide harmonic-suppressed band is presented. An accurate analysis of the parallel coupled line with an open stub (PCL-OS) is carried out. The PCL-OS structure shows excellent low pass filter and harmonic-suppression characteristics, which is useful for designing a low pass filter unit cell (LUC) with a reduced size. The designed Wilkinson balun at a 2.45 GHz center frequency not only shows an excellent harmonic suppression including the 5th harmonics up to 14 GHz over 15 dB, but it also has an area reduced to 48% of the conventional one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1237-1242
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• 2016

In this paper, the low pass filter with harmonics suppression and rejection using parallel coupled-line and radial type open stub is presented. And the resultant characteristic of the proposed low pass filter is that the harmonics are suppressed and rejected in wide bandwidth due to the parallel coupled-line structure. The open stub of a low pass filter is constructed in radial type which can be used to adjust the size of filter. The size of the proposed low pass filter is $6.98{\times}7.60mm2$ and the cut off frequency is 2.45 GHz. And the filter is economical in unit cost and can be constructed easily and has the merit of mass product because the filter is composed of distributed element. Also, the widely rejected harmonics is 128 % in the bandwidth and the insertion and return losses of the low pass filter are 1.07 dB and 19.5 dB, respectively.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.153-160
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• 2007

In this paper, the exact analysis of the parallel coupled line with open stub is presented. This structure shows LPF characteristics with broad stopband and sharp skirt characteristics. We derived the exact Z-matrix expression of the structure. In order to show the validation of the expression we designed $3^{th}$ order Chebyshev LPF using the structure. The simulated data excellently agreed with the predicted values by the calculation using the derived expression.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.3
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• pp.68-73
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• 2011

In this paper, a compact-narrow open stub band-pass filter with parasitic-signal of low frequency range and second harmonics rejected using the parallel coupled line and FLCLM(Frquency Locked Controlled Length Method) is proposed. The characteristic of the parallel coupled line can be rejection for parasitic-signal of low frequency range and second harmonics. In last filter of experimental results show that insertion loss is 1.2 dB and return loss is 14.8 dB, and the fractional bandwidth is 10 % at the center frequency of 5.8 GHz. In additional, the rejection for parasitic-signal of low frequency range and second harmonics are 28.9 dB and 28.8 dB, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.1-5
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• 2017

In this paper, we propose a wideband band-stop filter (BSF) in order to extend the stopband of the band-stop filter using a symmetric dual spurline and the coupled open stub. First, we know that the symmetric dual spurline structure is advantageous in widening the stopband, as compared to the asymmetric dual spurline structure. So we designed a band-stop filter that combines the electrically coupled open stub (ECOS) band-stop filter with a symmetric dual spurline. We can greatly extend the stopband, when it is combined with the dual spurline and electrically coupled open stub on a microstrip transmission line, without any size increment. The stopband of the proposed band-stop filter is extended by approximately 244% (rejection depth: -20 dB) compared with a band-stop filter without a dual spurline.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.40-45
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• 2008

In this paper, the exact analysis of the parallel coupled line with open stub and an application to branch-line hybrid are presented. The Z-parameter of the parallel coupled line with an open stub is derived. The structure shows the characteristics as a lowpass filter unit cell(LUC) with wide stop band. Using the characteristics we designed a miniaturized branch-line hybrid with wide harmonic-suppressed band. The size of the new branch-line hybrid is a half of the conventional branch-line hybrid. The frequency response is the same with that of the conventional one near 1.7 GHz center frequency. Including the fifth harmonics, up to 12 GHz spurious responses are suppressed below to -20dB.

• 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.

• Journal of electromagnetic engineering and science
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• v.15 no.1
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• pp.31-36
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• 2015

The design of a new compact band-pass filter is proposed, which is based on the microstrip composite right- and left-handed transmission- line (CRLH-TL) structure. Particularly, the interdigital coupled (IDC) lines of the CRLH geometry are proposed to be parted by inserting open stubs to meet the specifications on the passband. In addition, there is another pair of stubs to complete the design in a limited space. These are considered in the TL-based analysis and the design parameters are calculated by genetic algorithm optimization. The measurement is shown to be acceptable and agreeable with the circuit and electromagnetic field simulations. In addition, the zerothorder resonance (ZOR) phenomenon is verified.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.36-43
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• 2004

In this paper, we proposed a novel compact microstrip lowpass filter with an ultra-wide stopband and prominent cutoff sharpness using slot on the ground plane and microstrip shunt open stub. The microstrip shunt open stub and slot exhibit the different stopband response. The combined characteristics of these structures gives the ultra-wide stopband characteristics and the coupling effect between slots on the ground plane makes the prominent cutoff sharpness. The fabricated microstrip lowpass filter with the size of 20.1 mm ${\times}$ 18.7 mm has -3 ㏈ cutoff frequency at 1.187 ㎓ and -20 ㏈ stopband from 1.33 ㎓ to over 20 ㎓ and the insertion loss in the passband is less than -0.4 ㏈ form DC to 1 ㎓.