• Title/Summary/Keyword: bandpass filter

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A Varactor-Tuned RF Tunable Bandpass Filter with Improved Passband Flatness

  • Kim, Byung-Wook;Yun, Du-Il;Yun, Sang-Won
    • Journal of electromagnetic engineering and science
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    • v.2 no.2
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    • pp.124-127
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    • 2002
  • A RF tunable bandpass filter using dielectric resonators and varactor diodes is redesigned to improve the passband flatness. Since the tunable liters are generally of narrow bandwidth and the Q value of the varactor diode is usually very low, the passband flatness is strongly deteriorated by sizeable distortion loss. To remedy this problem, we construct modified Chebyshev type filter by use of network synthesis techniques. The key of modified Chebyshev type filter is the rearrangement of the passband poles to improve the passband flatness. To maintain the constant passband bandwidth, design techniques of input/output stage and coupling windows are also applied. Experimental results show that the passband flatness can be improved by purposed method without any additional RF amplitude equalizer.

A Study on The Design of Planer Comb-Line Bandpass Filter Using Equivalent Circuits of Asymmetrical Coupled Line (비대칭 결합선로 등가회로를 사용한 Comb-line 구조의 대역통과 여파기 설계)

  • Yun, Jae-Ho;Park, Jun-Seok;Kim, Hyeong-Seok
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.8
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    • pp.368-374
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    • 2002
  • In this paper, we introduce a procedure to obtain a equivalent circuit of comb-line band pass filter. By employing equivalent circuits of each asymmetrical coupled line. we composed the full equivalent circuit of comb-line bandpass filter and derived simple design equations for extracting each line's impedance. To show the validity of design equations, we simulated and fabricated a planar type comb-line bandpass filter, which has center frequency 1.8㎓, band-width 50㎒ and four resonators. The resulting filter is very compact, have broad stop band with the second pass band centered at four times the center frequency of the first pass band. The experimental results show exact performances of design specification.

Design of the Miniaturaized UHF Bandpass Filter with the Wide Stopband Using the Inductive-Coupling Inverters and Metamaterials (유도 결합형 Inverter와 Metamaterial을 이용한 넓은 저지 대역을 갖는 소형 GSM 대역 통과 여파기의 설계)

  • Ju, Jeong-Ho;Kahng, Sung-Tek
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.2
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    • pp.95-101
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    • 2008
  • This paper presents a novel bandpass filter design method for suppressing spurious response in the GSM band and effectively reducing the overall size with the unbalanced-conditioned metamaterials. Compared to the conventional bandpass filters based on half-or quarter-wave resonators, the CRLH(composite right/left-handed) bandpass filter works excellently in harmonic-suppression by 40$\sim$50 dB and 80 %-miniaturization using the zero-order resonators bridged by Inductive-coupling Inverters suggested first time. The proposed technique, with the equivalent circuit and dispersion diagram, is validated by performance predictions and experiments.

The Design of Miniaturized Waveguide Bandpass Filters with Improved Spurious Characteristics (Spurious 특성이 우수한 계단형 불연속 구조 소형 도파관 대역통과 여파기의 설계)

  • 성규제;윤상원
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.2
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    • pp.237-246
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    • 1999
  • A miniaturized waveguide bandpass filter is designed by combining a corrugated lowpass structure and a highpass configuration based on the cut-off effect of waveguides. It is smaller than the conventional waveguide bandpass filter composed of half-wavelength resonators and has wider spurious free characteristics. Optimized design data for a seven-order waveguide bandpass filter with the symmetrical structure are given at the center frequency of 10 GHz with 800 MHz bandwidth. Measured bandwidth of the center frequency of 9.97 GHz is 840 MHz and measured insertion loss is 0.97dB, The length of the bandpass filter is 64.38mm. The first spurious response is produced at 26.1 GHz.

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The Design of RF Active Bandpass Filters using Active Impedance Inverters (능동 임피던스 인버터를 이용한 RF 능동 대역 통과 여파기의 설계)

  • 전영훈;윤상원
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.5
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    • pp.672-679
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    • 1999
  • This paper describes the design method of active bandpass filters which employ active impedance inverters. Several authors have reported active bandpass filters. However, the functional description of the active blocks in the filters have not been throughly studied. In this paper, the active inverter block of the bandpass filter has is analyzed in the view point of filter design. The designed 3-pole bandwidth filter has its insertion gain of 24 dB at the center frequency of 865 MHz with 75 MHz bandwidth. The noise figure of the active bandpass filter is less than 2.5 dB within its passband.

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A Novel RF Active Bandpass Filter with Low Noise Performance (저잡음 특성을 갖는 새로운 RF 능동 대역통과 여파기)

  • 이재룡;윤상원
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.8
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    • pp.748-753
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    • 2002
  • In this paper, a new topology of a active capacitor is proposed in order to apply the resonator in the design of RF active bandpass filters. Through the noise analysis of the active capacitor, the optimized low noise design process is also presented, Due to the low noise performance of the proposed active bandpass filter, it can be used in the RF front-end of the receivers. In designed 2-stage active bandpass filter at 1.9 GHz shows insertion loss of 0 dB, noise figure of 2.6 dB, and OIP3 of 8 dBm.

Microstrip Bandpass Filter for Spurious Resonant Mode Rejection using Metameterial Transmission Line (메타매질 전송선로를 이용한 불요 공진모드 제거용 마이크로스트립 대역통과 필터)

  • Yang, Doo-Yeong;Lee, Min-Soo
    • The Journal of the Korea Contents Association
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    • v.9 no.12
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    • pp.566-571
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    • 2009
  • In this paper, microstrip bandpass filter combined DCRLH metameterial-cells with a hairpin resonator is designed and fabricated to be transferred only fundamental passband signal, and removed a spurious resonant mode occurring when filter design using a microstrip transmission line is done. The bandpass filter is composed of CCRLH hairpin resonator and DCRLH interdigit metameterial-cells. The hairpin resonator with CCRLH property is implemented between two DCRLH interdigit metameterial-cells with DCRLH property, which is parallel to input port and output port. The interdigit metameterial-cells suppress spurious harmonics occurring on the higher order frequency and improve a filter performance. Insertion loss of the fabricated microstrip bandpass filter on the passband from 1.91GHz to 2.41GHz is 0.2dB, and attenuation on the stopband from 3GHz to 7.7GHz is bellower than -30dB. Therefore, this filter has a good performance for both mobile communications of WCDMA and wireless internet of WiBro.

Computer aided design of miniaturized wavegude bandpass filters (소형 도판관 대역통과 여파기의 CAD 설계)

  • 성규제;박정호;윤상원;장익수
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.9
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    • pp.15-20
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    • 1997
  • Waveguide bandpass filters using E-plane or H-plane discontinuities have been used in many satellite communication systems. Since the transmitter and receiver of such systems tend to be getting smaller, components such as bandpass filters must also be reduced in size. In this paper, in order to reduce the waveguide, itself, of which bandpass filters consist, double plane step waveguide discontinuities are considered. They are analyzed using the mode matching method and the genralized scattering parameter of the cascaded structure is calculated. The characteristics of the bandpass filter which is designed using the reduced size waveguide is optimized by OSA90$^{TM}$. The bandpass filter has a good characteristics and smaller size than those made of the E-plane or H-plane step discontinuities.s.

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Design of a Narrow-Band Bandpass Filter Using Microstrip Open-Loop Resonators With Coupled and Crossing Lines (결합 및 교차 선로를 갖는 마이크로스트립 개방루프 공진기를 이용한 협대역 대역통과 여파기 설계)

  • 안승현;이영구;이문수
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.5
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    • pp.1011-1016
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    • 2001
  • In this paper, a narrow-band bandpass filter using microstrip open-loop resonators with coupled and crossing lines is designed and fabricated. This filter has many advantages such as compact in size, low weight and the characteristic of the elliptic-function narrow-band bandpass filtering. The configuration consists of two identical microstrip open loop resonators, coupled line and crossing line. By using open loop resonators, the size of the filter can be reduced about 50% compared with the ring resonators. A crossing line gives two notchs in the stopband, which have sharp selectivity in the passband. Centered at 2.455GHz, the calculated microstrip bandpass filter shows a bandwidth of 1.22%, which makes it very attractive for application in the wireless LAN. The filter is fabricated by photo-etching process. The fabricated bandpass filter shows that the bandwidth is 0.85% for 2.458GHz and the size is only $2.6cm\times1cm$.

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A Design of Narrowband Bandpass Filter using High-Temperature Superconductor (고온 초전도체를 이용한 협대역 대역통과 여파기 설계)

  • 윤형국;윤영중;김성민;이상렬
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.9B
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    • pp.1668-1675
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    • 1999
  • In this thesis, a narrowband bandpass filter using HTS is proposed for the multiplexer of the satellite communication subsystems. The proposed structure using HTS provides the narrower band and the lower insertion loss characteristics than the conventional parallel-coupled-line bandpass filter. The filter structure using hairpin-line only cause the spurious modes due to the surface waves. But these modes can be lessened by using the hybrid hairpin-line/parallel-coupled-line proposed in this thesis. The narrowband bandpass filters using HTS at the operation frequency of 14.25 GHz are fabricated to have the narrow bandwidth less 1% and the insertion loss less 3dB in comparison with the normal metal microstrip filter with the same three poles. The experimental results show that the filter using HTS has the characteristics of the narrower bandwidth and less insertion loss and can be fabricated with more compact size in comparison with the bandpass filter using normal metal.

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