• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.372-378
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• 2002

In this paper, a narrow-band waveguide channel fitter has been designed and realized for Ku band satellite transponder. Group-delay and amplitude variations of the channel filter have been minimized using a 2-pole reflection type equalizer. The channel filter has been designed to have the 8-pole elliptic response for high frequency selectivity. Dual-mode technique has been adopted for reducing mass and volume of the channel filter and equalizer. The channel filter and equalizer have shown good performance for satellite transponder.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.284-290
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• 2004

In this paper, two types of thin nim bulk acoustic resonator(TFBAR) ladder filters are desisted and fabricated to analyze the effects of on-wafer inductor integration. To suppress the overmode phenomenon a 1 $\mu\textrm{m}$ thick air-gap is fabricated under the TFBAR and aluminum nitride is used for piezoelectric material, while platinum is employed for the top and bottom electrodes. The Tx filter in a duplexer, which usually has a steeper skirt characteristics o the right side of the passband, is designed with four serial and two shunt resonators, namely, a 4/2 stage. Similarly, the Rx filter is devised with a 3/4 stage to create a mirrored image of the Tx filter passband characteristics. Fabricated on-wafer spiral inductors with underpass reveals the Q factor of 5～9 at 2 ㎓. Inductor integrated filters have approximately 10 to 12 ㏈ out-of-band rejection improvement, when compared to the original filters.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.381-383
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• 2006

본 논문에서는 5.8Ghz ISM대역 평행 결합선로 대역통과 여파기를 설계 제작하였다. 긴본적인 설계는 저역통과 여파기에서 대역통과 여파기로 변환한 후, 직 병렬 공진기를 이용한 설계와 J-인버터를 이용해 평행 결합선로 대역통과 여파기를 구현하였다. 2개의 공진 주파수를 실제로 구현하기 어렵기 때문에 하나의 공진기만을 사용하기 위해 인버터를 사용하였다. 또한 실제적인 마이크로스트립 라인의 layout크기를 결정하기 위해 우수 기수 모드 임피던스를 해석하고 근사식을 통해 스트립라인의 치수를 결정하였다. 이런 과정을 토대로 5.8GHz ISM밴드용 평행 결합선로 대역통과 여파기를 설계, 제작하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.95-100
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• 2006

In this paper, we designed amplitude equalizer which is composed of amplifier, complementary shaping filter and attenuator in order to improve flatness of high order bandpass filter. We modified Chebyshev polynomial and calculated the prototype elements for complementary shaping filters by network synthesis. The amplitude equalizer is realized that it connects the 4th order complementary shaping filter designed by using calculated the prototype elements to the amplifier compensating for insertion loss and improving return loss, and with the attenuator for gain control. Using proposed amplitude equalizer, We certificated improvement in flatness of 13th order bandpass filter at WiBro band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.565-573
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• 2000

In this paper, a interdigital microstrip bandpass filter is designed. A interdigital microstrip bandpass filter has many advantages such as insertion return loss, lower return loss, higher frequency selectivity and smaller in size in comparison with the conventional coupled line filter. A interdigital microstrip bandpass filter consists of quasi TEM-mode strip line resonators between parallel ground plant. Each resonator element is a quarter wavelength long of the center frequency and is short circuited at one end and open circuited at the other end. In the filter design, Ensemble software is used. Experimental results show that the bandwidth of interdigital microstrip bandpass filter is 2.52GHz, insertion loss is -1.8dB and return loss is -17.0dB at 11.20Hz.

• 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 $2.6cm\times1cm$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.805-814
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• 1999

In this paper, elliptic function bandpass filters using ceramic coaxial resonators are designed. Since elliptic function filters have better performance of frequency selectivity than those based on Butterworth or Chebyshev, therefore it is possible to make better use of limited frequency resources. Elliptic function bandpass filters using ceramic coaxial resonators are designed for reducing it's size, weight, cost and for easy manufacturing and tuning. From measurements, an accurate resonator model is obtained and the coupling coefficient values are extracted. Based on these results, elliptic function bandpass filters are designed. The experimental results have shown that the 8th order elliptic function filter of 959 MHz center frequency with 28 MHz bandwidth using coaxial ceramic resonators have about more tan 17 dB return loss, 5 dB insertion loss, more than 20 dB attenuation at $f_c\pm$5 MHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1556-1562
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• 2003

In this paper, a new representations of extended threshold Boolean filter(ETBF), called SA filter, is introduced. The structure of this representations is a one of multistage filters. The first stage is subfilters of nonlinear filters such as maximum, minimum, or exclusive-OR operators. The second stage is linear combination of Int stage outputs. Although the structure of this representations is very similar to SAM filters, SA filters encampass all ETBF not subset of ETBF.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.301-310
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• 2004

In this paper, a compact dual-mode filter structure without coupling gaps is proposed. The novel design is achieved by embedding a pair of equal crossed slots and spur-lines. Without coupling gaps between feed lines and patch resonator, the new filter can provide low insertion loss. It is found that this design has wide coupling range for dual-mode operation. It means that these characteristics of the proposed filter can reduce uncertainty in fabrication. By using two PIN diodes mounted inside a pair of spur-lines, the proposed structure works as a switchable filter. Also, it has a size reduction of about 34.7 %, compared with conventional dual-mode filters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.8-13
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• 2010

In this paper, a new hairpin type strip-line BPF(Band Pass Filter) improving the suppression performance of unwanted frequency signal is studied. A modified hairpin filter is designed by classical hairpin filter design methodology and is realized by newly placing structure of designed filter. And a newly formed coupled-line effects between modified bilateral symmetry structures make the transmission zeros. Each transmission zeros can shift its frequency to wanted frequency by tuning a certain part of filter. To investigate the validity of this novel technique, an order-5 Chebyshev BPF centered at 9.2 GHz with a 15 % FBW(fractional bandwidth) were used. According to design and measurement results, a good performance of insertion loss of 0.8 dB and unwanted signal suppression of maximum 50 dB is achieved at full input/output ports.