• Title/Summary/Keyword: 대역저지 필터

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Design of Closed-Form QMF Filters with Maximally Flat and Half-Band Characteristics in the Frequency Domain (주파수 영역에서 최대평탄과 하프대역 특성을 갖는 폐쇄형 QMF 필터들의 설계)

  • Jeon, Joon-Hyeon
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.44 no.4 s.316
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    • pp.70-77
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    • 2007
  • Two kinds of QMF(Quadrature Mirror Filter) pairs are used in JPEG2000 standard, which don't have QMF distortions. However, the QMF pairs have the main disadvantages such that there are gentle roll-off rate, ripples in the passband and unequal band decomposition. In this paper, Maxflat(maximally flat) QMF pairs with a half-band gain are proposed for overcoming these problems. Maxflat QMF pairs are realized due to generalized closed-form formulas, and the filters have maximally flat response in the passband/stopband as well as sharp roll-off rate in the transition band. Comparing proposed filters and JPEG2000's filters in frequency domain, it is found that proposed filters have better performance JPEG2000's filters. Moreover, Maxflat QMF pairs show stopband-attenuation exceeding 200 dB almost everywhere.

Dual-Band Compact Broad Band-Pass Filter with Parallel Coupled Line (평행 결합 선로를 갖는 이중 대역의 소형 광대역 대역 통과 필터의 설계)

  • Choi, Young-Gu;Shrestha, Bhanu;Yoon, Ki-Cheol;Lee, Jeong-Hun;Hong, Tae-Ui
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.12
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    • pp.1423-1431
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    • 2010
  • In this paper, the dual-band compact broad bandpass filter using parallel coupled line is proposed. The proposed filter has reduced size and can be controlled bandwidth. And it is also possible to operate in the dual-band purpose. Futhermore, the inserted bandstop fiilter with T-type configuration is also possible to operate in the same purpose. The dual-band bandpass filter has the first operating frequencies and its bandwidth which are 5.8 GHz and 60 % respectively and the second operating frequency and the bandwidth are 16.2 GHz and 60 % respectively. The insertion loss and the return loss of the first frequency has 0.4 dB and 17.4 dB and the insertion loss and the return loss of the second frequency has 0.62 dB and 19.8 dB, respectively.

An Analysis on Audio Quality Deterioration of Acoustic OFDM (음향 OFDM의 음질 저하 원인 분석)

  • Cho, Ki-Ho;Yu, Hwan-Sik;Chang, Jun-Hyuck;Kim, Nam-Soo
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.2
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    • pp.107-111
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    • 2009
  • Acoustic OFDM is used for audible frequency band acoustic communication which employs loudspeaker as transmitter and microphone as the receiver antenna. Since acoustic OFDM can transmit about 1 kbps using 1600 Hz band. acoustic OFDM signal is inserted into the audio signal like music or speech, However. audio quality deteriorates definitely during the inserting process. This paper introduces a reason for audio quality deterioration and discuss how to reduce this phenomenon.

Fabrication and Design of a Compact Narrow Band Pass Filter Using Slot Type Split Spiral Resonators (슬롯형 분할 나선형 공진기를 이용한 소형 협 대역통과 필터 설계 및 제작)

  • Choi, Dong-Muk;Kim, Dang-Oh;Jo, Nam-I;Kim, Che-Young
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.4
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    • pp.38-42
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    • 2010
  • In this paper, a design method of the compact narrow band filter on the microstrip board is proposed using slot-type split spiral resonators. The design technique of this filter is based on cascading filter stages consisting of the combination of slot-type split spiral resonators, capacitive gaps between patches, and inductive grounded stubs with the meander configuration. By these means, it was possible to get the nearly symmetric frequency responses, adjustable bandwidths, compact sizes. And also excellent characteristic of the out-of-band rejection is achieved in contrast to the conventional filter design technique. The measured insertion loss shows good results about -3.47dB at the center frequency($f_0$=1GHz) and passband return loss is less than -12.62dB. The 3dB fractional bandwidth(FBW) is approximately 7.3%. The results of the frequency response measured on the fabricated band pass filter substrate show satisfactory agreement with the simulated frequency responses by the MWS(Microwave Studio) of CST in the region of interest.

An Algorithm of Optimal Design in Binary Transversal Filter (2진 횡단선 필터의 최적설계 알고리듬)

  • Lee, Kang-Ho;Choi, Jong-Soo
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.5
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    • pp.1-9
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    • 1989
  • In binary digital transmission system the band-limiting is required for the better transmission efficiency. But in the case of band-limiting the intersymbol-interference (ISI) usually takes place. In this paper, in an attempt to design band-limiting filter which has minimum ISI and maximum stop-band loss, first, making use of analog filter by combining Binary Transversal Filter (BTF) and analog filter (4th Butterworhfilter), we found the value that minimizes ISI phenomenon by getting step response of rectangular pulse resulting from BTF in time domain. Second, we found filter characteristic we want to in frequency domain for band-limiting and minimized the error. And then we obtained resistor value (Tap coefficient) in order to design algorithm for optimum filter. Also we showed the example of simulation in case we established the resistors with 3,5 and 7 respectively. With 7 resistors set, we identified that the ripple of about minus 30dB was taken place.

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Design of a Compact Narrow Band Pass Filter Using the Circular CSRR (원형 CSRR를 이용한 소형 협 대역통과 필터 설계)

  • Choi, Dong-Muk;Kim, Dang-Oh;Kim, Che-Young
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.11A
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    • pp.918-923
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    • 2009
  • In this paper, a design method of the compact narrow band filter on the microstrip board is proposed using complementary split-ring resonators(CSRRs). The design technique of this filter is based on cascading filter stages consisting of the combination of circular CSRRs, capacitive gaps between patches, and inductive grounded stubs with the meander configuration. By these means, it was possible to get the nearly symmetric frequency responses, adjustable bandwidths, compact sizes. And also excellent characteristic of the out-of-band rejection is achieved in contrast to the conventional filter design technique. The measured insertion shows good results about -4.0dB at the center frequency($f_0=1GHz$) and passband return loss is less than -9.4dB. The 3dB fractional bandwidth(FBW) is approximately 4%. The results of the frequency response measured on the fabricated band pass filter substrate show satisfactory agreement with the simulated frequency responses by the HFSS in the region of interest.

Harmonic Suppression Compact Microstrip Patch Antenna for IoT Sensor (고조파 억제를 위한 IoT 센서용 소형 마이크로스트립 패치 안테나)

  • Lee, Hyun-Seung;Lim, Jeong-Taek;Jung, Bang-Chul;Kim, Choul-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.85-89
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    • 2017
  • This paper proposes an antenna incorporating a bandstop filter to miniaturize the rectenna used for wireless power transmission with the emerging interest these days. To suppress the harmonics that can be re-radiated, this paper proposes a microstrip patch antenna that can suppress the harmonics while maintaining the size of the antenna by inserting a U-slot, which acts as a bandstop filter, on the ground plane of the antenna. As a result, S11 of the second harmonic(4.6GHz) was reduced from -5.61dB to -0.338dB and the efficiency was suppressed significantly from 29.76% to 1.5%. In addition, the maximum gain was reduced to -12dBi from 2.89dBi. On the other hand, at the fundamental frequency (2.45GHz), the S11 value was reduced from -18 dB to -15 dB, and the efficiency was reduced slightly from 68.2% to 60%. In the case of applying a microstrip antenna combined with the proposed bandstop filter to a rectenna, it is believed that the harmonics that degrade the performance of the rectenna can be removed effectively while reducing the large area occupied by harmonic suppression.

Lower Characteristic Impedance Based Compact f λ0/4 Short-Circuited Stub UWB Bandpass Filter with WLAN Stopband (저특성 임피던스의 λ0/4 단락 스터브 기술을 이용한 WLAN 저지 대역을 가지는 UWB BPF)

  • Hoa, Duong Thai;Joo, Hyo-Suk;Kim, Ihn-Seok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.4
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    • pp.323-332
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    • 2009
  • In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.

A Reflection Type Band-rejection Filter Using the Frequency Selective Loads (주파수 선택적 부하를 이용한 반사형 대역저지 필터)

  • 김윤조;정승환;황희용;정중성;박준석
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2002.11a
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    • pp.141-145
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    • 2002
  • In this paper, we have implemented the reflection type band-rejection filter by employing the 3-㏈ hybrid and the frequency-selective loads. The frequency-selective loads have been achieved with the 3-pole bandpass filter terminated by a 50-ohm load. The reflection type band-rejection filter is less sensitive to unloaded Q-factor of resonator than the conventional one. Measurements and simulations on the presented band-rejection filter in this paper show the excellent performances in passband and rejection-band.

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Optimal design of linear-phase FIR digital filters with flat passbands and equiripple stopbands (평탄한 통과대역과 등리플 저지대역을 갖는 선형위항 FIR 디지탈 필터의 최적설계)

  • 정부영;이영국;김영권
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10b
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    • pp.437-441
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    • 1987
  • We have studied a new technical approach for the design of digital FIR filters with flatness in the passband, and equiripple attenuation in the stopband using the program of J.H. McClellan, T.W.Parks, L.R.Rabiner and the flatness property. The design technique directly loads to structures that have low passband sensitivity properties.

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