• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.282-289
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• 2014

In this paper, the UWB (Ultra Wide Band) band-pass filter (BPF) with compact-size using impedance mismatching in transmission line and SIR (Stepped Impedance Resonator) instead of open stubs is presented. The proposed BPF have 103 % of bandwidth and 11.2 GHz of center frequency, respectively. In additional, the operation frequencies of the suggested BPF are 4.8 GHz to 16 GHz. In this structure, the length of the transmission line is reduced to half compared with the original one by impedance mismatching technique with low frequency band (sub harmonics) and harmonic components. Also, the open stub can be used for SIR due to reduced size. Experimental results show that the insertion and return losses are 0.35 dB and 15.1 dB, respectively and the filter size is $8.92{\times}10.6mm^2$. The proposed BPF is in good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.761-770
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• 2008

Impedance or admittance inverter is a conceptual 2-port device frequently used in microwave filter design. In this paper, the equivalent circuit using inverter for general loss less 2-port circuit is presented. Our equivalent circuit can be directly and easily represented with z- or y-parameters compared with the conventional methods. Based on the representation, the derived results for various coupled lines such as parallel coupled line and anti-parallel coupled lines are compared ours. In addition, the results of other workers for improvement of the distortion in frequency response of microstrip coupled line filter are derived using our representation and compared. The proposed equivalent circuit shows the difference with conventional equivalent circuit so the conventional design method can not be applied to parallel coupled line filter with our representation. So in this paper the novel design method is proposed and we showed the method yields more accurate design results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.884-890
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• 2008

In this paper, Characteristics responded to frequency of a band-pass filter with admittance inverters(J-inverters) is considered. As a result, it is confirmed that attenuation characteristics of upper and lower frequency is asymmetric. And a modified circuit and design formulas are proposed to improve the asymmetric attenuation characteristics. By confirming the simulated and measured results that are got from designed and made a experiment on the band-pass filter with the proposed circuit and formulas for design, we confirm that the asymmetric attenuation characteristics of the band-pass filter are improved without any optimization or iterative design procedures and additional calculation efforts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1707-1717
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• 1998

Polyphase filtering techniques is used to suppress the narrowband jammer signal such as USDC TDMA overlaying the band occupied by DS-CDMA system. In the proposed jammer suppression, the received signal is separated into 64 subchannels in two stages by polyphase filtering and the location of the narrowband jammer signal is determined by measuring each subchannel power and the contaminated subchannels are simply blocked. The $E_{b}/N_{0}$ 0/ improvement of the CDMA system from jammer suppession was outstanding. The $E_{b}/N_{0}$ degradation in comparison with a performance of no jammer is around 0.8dB in the worst case. The results are also compared with those of linear prediction jammer suppression. The implementation of the ployphase jammer suppression requires great amount of data processing and computation compared to linear predication filter. Thus it is more appropriate to implement with a ASIC rather than WITH several DSPs for user terminals of forward link.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.542-550
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• 2001

In this paper, a channel combiner is designed to combine two adjacent digital TV channels without interference to transmit these channels with one broadband antenna. A constant impedance type combiner, consisting of two identical bandpass filters and two identical 3 dB power combiners, is chosen as a channel combiner. The bandpass filter used in the channel combiner also suppresses out-of-band signal caused by digital transmitter's non-linearity. H-plane type bandpass filters and branch-line fewer combiners are adopted in the design. The simulated results of the designed bandpass filter and power combiner show excellent agreement with the theoretical results. Finally, a channel combiner is designed by combining filters with rover combiners and the characteristics are simulated. It is shown that the designed channel combiner shows excellent performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.598-605
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• 2012

In this paper, a multi-layer dual-band bandpass filter using aperture-coupling is proposed. Two coupling paths are formed with the two apertures which exist between two dual-mode resonators. The coupling coefficients can be adjusted without changing the shape of resonators. The bandwidth of the second passband can be adjusted without affecting the bandwidth of the first passband using the size of an aperture between stubs of the dual-mode resonator. The aperture coupling mechanism is theoretically analysed. The dual-mode bandpass filter for the 2.4 GHz WLAN, 3.5 GHz WiMax was designed and fabricated. The fabricated filter shows centered 2.45 GHz and 3.5 GHz with 9 % and 8 % of the bandwidth.

• 전기의세계
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• v.32 no.8
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• pp.486-493
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• 1983

기존 Echo제거기의 여파기계수를 binary representation할 때 bit수를 줄이기 위하여 자동이득 조절기를 사용한 새로운 Echo제거기를 제안하였다. 적응여파기 계수수가 55이고 .rho.e=16dB, P/S.leq. dB일때 P.leq.0 dB, S>-42 dB인 경우 새echo제거기는 20bit로서 8bit로 규격화된 디지탈 Processor 또는 기억소자등을 사용하면 30%의 bit절약을 가져온다. 수학적 operation은 대단히 경미하게 증가하며 수렴속도도 훨씬 빠르다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1083-1089
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• 2007

In this paper, we applied the CMRC to a resonator to improve the harmonic characteristic of VCO. The CMRC filters have some advantage. It is a small size as well as easy to manufacture than PBG, DGS and other filters. This paper was proposed by using CMRC for a VCO. The second harmonic of -42.83 dBc and the phase noise at 100 kHz offset of -95.83 dBc/Hz was achieved, respectively. The VCO has better second harmonic character by 15.73 dB and phase noise by 31.13 dB in case of CMRC applied behind a resonator than CMRC used as a resonator.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.2
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• pp.22-27
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• 1978

An improved active R filter is proposed which contains only resistors and two operational amplifiers represented by their single pole model. The filter has very low sensitivities to all circuit parameters, is suitable for low frequency and low 9 applications in addition to high frequency and high 0, and realizes various biquadratic transfer functions simultaneously with lower resistance ratios. The independent control of design specifications is possible in the circuit. Experimental results in laboratory are presented.

• The Journal of the Acoustical Society of Korea
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• v.7 no.4
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• pp.13-21
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• 1988

In order to overcome the disadvantages of linear filters in certain cases of practical interest, a class of nonlinear filters(rank filters) are constructed based on a class of robust estimates, the rank estimates. A subclass of these filters, the limited-degree extended-averaging Wilcoxon filters, is then described as an interesting example of the rank filters with desirable characteristics. The properties of these filters are discussed and the performance of these filters are analyzed for ideal edges and narrow pulses.