• Journal of electromagnetic engineering and science
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• 제4권3호
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• pp.113-118
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• 2004

As an application of ring filters, a new and simple method to determine an inherent-ring-resonance frequency is introduced. The ring filter consists of a ring and two short stubs. They are connected at 90$^{\circ}$ and 270$^{\circ}$ points of the ring and the ring filter may be seen in such way that two filters are connected in parallel. Therefore, if the two powers of the two filters are out-of-phase at the output, the power excited at the input can not be delivered. That can be done by making difference in length of the two short stubs, and when a certain condition is satisfied, a frequency exists where all the excited power is reflected. That is the very inherent-ring-resonance frequency. In the lossless case, the return loss with the condition reaches 0 dB at the inherent-ring-resonance frequency but does not with conductor, dielectric losses and so on. Therefore, the effective loss tangent at a frequency of interest may be obtained correctly. To verify the method, two ring filters have been fabricated in microstrip lines and the measured results show good agreement with the predicted ones.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1549-1551
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• 1998

We have designed and developed narrow bandpass multipole filters for satellite communication using $YBa_2Cu_3O_{7-x}$(YBCO) thin films on MgO substrates. The superconducting film used in this study was prepared by laser ablation on one side polished MgO (100) substrates. A Nd:YAG laser was used to fabricate YBCO thin films. The wave length of the laser was 355 nm. The laser beam was focused onto a YBCO target rotating linearly to avoid deep craters that may eject macroscopic YBCO particles. The YBCO films were grown at $750^{\circ}C$ in the oxygen partial pressure of 200 mTorr. The deposited YBCO thin films were patterned by conventional wet-etching method. The transition temperatures of YBCO thin films were 85 - 88 K and the film thicknesses were about 5,000 $\AA$. By comparing the performances of normal-metal filters and YBCO filters, we observed that superconducting YBCO multipole filters have been showed superior performances at 77 K.

• 한국전자파학회논문지
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• 제13권8호
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• pp.819-826
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• 2002

본 논문은 $Ba_{0.5}$Sr$_{0.5}$TiO$_3$(BST) 박막을 이용한 대역 통과 여파기를 설계, 제작한 것으로 마이크로스트립 과 코플래너 웨이브가이드(CPW), CBCPW 전송 선로 구조에서 각 구조의 여파기 특성을 비교하였다. 제작된 여파기는 전압 0V 인가시 각각 6.4 GHz, 6.14 GHz, 6.04 GHz의 중심 주파수와 6 dB, 4.41 dB, 5.41 dB의 삽입 손실이 측정되었으며, 40V 인가시 중심 주파수 6.61 GHz, 6.31 GHz, 6.21 GHz와 삽입 손실 7.33 dB, 5.83 dB, 6.83 dB로 나타났다. 본 논문에서 제작된 각각의 대역 통과 야파기는 가변 범위가 약 3 % - 8 %이며, 무선랜 대역에 응용할 수 있도록 설계 및 제작되었다.다.

• 한국전자파학회논문지
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• 제8권5호
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• pp.442-451
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• 1997

본 논분은 정밀합성법에 의한 마이크로스트립 필터의 소형화를 다루고 있다. 정밀합성법을 이용하면 물리적 구현이 가능하면서 완전히 새로운 회로를 개별적인 소자들의 조합으로 설계할 수 있다. 복잡한 회로망 합성은 컴퓨터 소프트웨어를 이용하여 쉽게 처리한다. 이것은 최소의 소자를 사용하여 최적의 회로망을 구현할 수 있는 새로운 설계 절차이다. 정밀합성법을 이용하면 50-100 %의 대역폭을 갖는 광대역 필터의 설계가 가능하다 대역 동과 S 평면 프로토타입은 원하는 주파수에서 전송영점을 갖는 비리던던트(non-redundant) 펼터 합성법에 의해 만들이진다. 저지대역 중심주파수에서 $\lambda$/4 감이인 전송선로를 사용하기 때문에 필터의 면적을 크게 줄일 수 있게된다.

• 한국정보통신학회논문지
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• 제13권7호
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• pp.1255-1260
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• 2009

마이크로스트립 인터디지털(interdigtal) 여파기는 공진기의 폭, 길이, 공진기 사이의 간격과 탭의 위치로 설계하는데, 설계파라미터의 수를 줄이는 것이 구현 측면에서 유리하다. 본 논문에서는 마이크로스트립 인터디지털 여파기의 설계파라미터 중에서 공진기의 폭을 고정시킨 것과 서로 다른 폭을 갖는 두 종류의 여파기를 국내 UWB(Ultra Wide-Band) 주파수 대역에서 설계 및 구현하였다. 여파기의 성능 측정 결과 공진기의 폭을 고정한 low-band high 여파기의 삽입손실은 1.49dB, -10dB 대역폭은 750MHz였고, 4.8GHz에서 -35.7dB의 감쇄특성을 가졌으며, S11은 -13dB 이하로 측정되었다. 공진기의 폭이 서로 다른 low-band 여파기는 삽입손실 1.6dB, -10dB 대역폭은1.63GHz로 측정되었고, S11은 -8dB 이하로 측정되었다.

• Progress in Superconductivity
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• 제4권2호
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• pp.132-136
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• 2003

Extremely selective high temperature superconducting (HTS) band -pass filters were developed for the base transceiver station applications of Digital Cellular communication Service (DCS). The filters have a bandwidth of 25 MHz at a center frequency of 834 MHz. There are 12 resonators which have spiral-meander microstrip-line structures in order to reduce far-field radiations with a reasonable tunability. As a result, the size of filters is 5 mm $\times$ 17 mm $\times$ 41 mm. Device characteristics exhibited a low insertion loss of -0.4 dB with a -0.2 dB ripple and a return loss better than -10 dB in the pass-band at 65 K. The out-of-band signals were attenuated better than 60 dB about 3.5 MHz from the lower band edge, and 3.8 MHz from the higher band edge.

• 한국전자파학회논문지
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• 제11권5호
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• pp.697-706
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• 2000

In this paper, new bandpass filters that are composed of microstrip ring resonators with the center frequency of 5.775 GHz and the bandwidth of 100 MHz are presented. For the suppression of the unnecessary harmonics, lowpass filters are inserted into the feedlines and ring resonator itself, respectively These bandpass filters show good microwave characteristics with the harmonic suppression ratio of about 39 dB and 35 dB, respectively. Also, the varactor-tuned microstip ring bandpass filter with harmonic suppression is suggested and the tuning bandwidth of more than 450 MHz is obtained.

• ETRI Journal
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• 제29권4호
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• pp.533-535
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• 2007

For the purpose of decreasing intermodulation distortion, a new multi-harmonic suppression band-pass filter based on a microstrip radial stub is studied. Compared with traditional resonator filters, the new filter can suppress the second, third, and even fourth harmonics directly. The dimension of the filter is about $0.3\;{\lambda}_{g^0}{\times}0.13\;{\lambda}_{g^0}$ (${\lambda}_{g^0}$ is the guiding wavelength at the resonant frequency). Only one gap was introduced, so lower insertion loss can be obtained. Basic agreement between the measured and simulated results has been achieved.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.67-68
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• 2006

A suspended microstrip line structure over mushroom-like SMPs is designed and is applied to a dual-frequency and dual-polarization microstrip patch antenna. This structure has a distinctive and sharp rejection band and provides near 0 dB insertion loss outside the rejection band. Applying the structure to the conventional DFDP antenna enhanced the isolation between the two ports more than 20 dB. The structure is expected to have a wide range of applications in antennas and filters due to its compactness and integrability in circuits.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권7호
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• pp.395-400
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• 2004

In this paper, the four-pole elliptic function microstrip filter at 2.4GHz band with fractional bandwidth of 4% is realized using compact miniaturized hairpin resonators. The parallel algorithm FDTD method is used to analyze S-parameter of hairpin resonator filter more accurately, and to calculate the electric coupling and magnetic coupling among the hairpin resonators. Absorbing boundary conditions for mesh termination used Sulivan's simplified PML and the FDTD code was paralleled by MPI for IBM SP2 which had enhanced calculation speed. The experimental measurements are performed by HP8720D vector network analyzer. Measured results on fabricated hairpin type cross coupled bandpass filters show good agreements with theoretic results.