• 한국전자파학회논문지
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• 제17권12호
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• pp.1199-1205
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• 2006

본 논문은 두 개의 대역 저지 반파장 슬롯을 방사체에 삽입하여, 향상된 대역 저지 특성을 갖는 보우타이형 광대역 모노폴 안테나를 제안하였다. 제안된 안테나는 전자기적으로 급전된 보우타이 형태의 방사 평면과 접지면 사이에 반원 모양의 기생 접지면을 추가한 구조이다. 향상된 대역 저지 특성을 얻기 위하여 두 수평 슬롯간의 결합량을 조절하였다. 측정된 안테나는 $4.96{\sim}5.51GHz$에서 저지 특성을 갖고, $2.7{\sim}6.9GHz$에서 정재파비 2.0 이하를 만족하는 광대역 특성을 나타내었다. 단일 슬롯 사용과 비교하면, 넓은 저지 대역폭과 향상된 스커트 특성을 나타내었다. 측정된 안테나의 방사 패턴은 이상적인 모노폴 안테나와 유사한 특성을 가지며, 저지 대역에서의 안테나 이득은 다른 동작 주파수에 비해 x-z 평면을 기준으로 $5{\sim}10dB$ 이상 감소되었다.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.186-191
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• 2011

This paper presents a simple and effective method for improving stopband rejection characteristics of previously studied dual-band filters. Small electric couplings were applied to the symmetrically positioned shunt resonators, which divided each transmission zero into two transmission zeros without any effect on passbands. We were able to achieve improved stopband rejection characteristics by these additional transmission zeros. For the filter application, we designed a dual-band filter with improved stopband characteristics using microstrip quasi-lumped elements. The electric couplings that control the location of transmission zeros are controlled by the distance between symmetric open stubs of the filter. The filter was fabricated with a relative dielectric constant of 3.5 and a thickness of 0.76 mm. The fabricated filter has a small size ($14.6{\times}13.2{\times}0.76$ mm) and a low insertion loss when compared with conventional filters.

• 전기전자학회논문지
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• 제22권3호
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• pp.793-799
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• 2018

An improved design of Ultra Wide Band(UWB) Bow-Tie antenna, which can control an enhanced wide stop-band, is presented. The mutually coupled slot-pair improves and controls the rejection band. The UWB antenna is composed of an electromagnetically coupled Bow-Tie patch and a parasitic ground patch, whose working frequency is extended to full UWB range in this work. By adding slot-pairs on the main patch and optimizing, they can give any requested wide rejection bands and sharp skirt characteristics, as is often required for UWB antennas and multi-band antennas. All the parameters are precisely calculated by an adequate optimization method. The Particle Swarm Optimization(PSO) technique is appropriately adopted. The proposed design and method is proved to give and control the sharp-skirt wide stop-band to UWB Bow-Tie antennas.

• Transactions on Electrical and Electronic Materials
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• 제7권4호
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• pp.196-203
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• 2006

An air-gap type FBAR was designed using Leach equivalent model for analyzing a vertical structure of the FBAR. For the top electrode, Pt, and the bottom electrode, Au, of $1.2{\mu}m$ thickness and the piezoelectric of 0.8,urn thickness, the resonance and anti-resonance occurred at 2.401 GHz and 2.460 GHz, respectively. $S_{11}$ was increased and $S_{21}$ was decreased as the resonance area of FBAR was widened. We observed the characteristics of insertion loss, bandwidth and out-of-band rejection of ladder-type FBAR BPF by changing resonance areas of series and shunt resonators and by adding stages. As the resonance area of series resonator was increased, insertion loss was improved but out-of-band rejection was degraded. And as the resonance area of shunt resonator was increased, insertion loss was degraded a little but out-of-band rejection was improved even without adding stages. We, also, changed the shape of the resonance area from square shape to rectangle shape to examine the effects of the resonator shape on the characteristics of the BPF. The best performances were observed when the sizes of series and shunt resonator are $150{\mu}m{\times}l50{\mu}m\;and\;5{\mu}m{\times}50{\mu}m$, respectively. Out-of-band rejection was improved about 10dB and bandwidth was broadened from 30MHz to 100MHz utilizing inductor tuning on $2{\times}2\;and\; 4{\times}2$ ladder-type BPFs.

• The Journal of the Acoustical Society of Korea
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• 제15권4E호
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• pp.14-20
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• 1996

The double mode SAW resonator filters have the serious shortcoming that out-of-band rejection above the passband is quite poor. Hence a new structure of the double mode filter is designed with the COM (Coupling Of MOdes) theory with better out-of-band rejection characteristics while keeping all the beauties of the conventional type. The second goal of the design is to reduce the planar size of the structure so that mass productivity of low frequency devices can be improved. For those purposes, several IDT's and relfector gratings are added to or subtracted from the conventional structure so that the modification can lead to better overall performance as a filter. As results of the investigation, several new double mode SAW resonator filter structures are developed. A new structure shows 10dB more out-of-band rejection that the conventional type with 25% reduced device size. Good agreement is demonstrated between the analytical results and experimental results for an illustrative 325MHz four pole resonator filter on 64°YX LiNbO3.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.78-81
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• 2000

A new type low-pass filter design method based on a coupled line and transmission line theory is proposed to suppress harmonics by attenuation poles in the stop band The design formula are derived using the equivalent circuit of a coupled transmission line. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range and low insertion loss. The seventh-order low-pass filter designed by present method Ins a cutoff frequency of 0.9 GHz with a 0.01 dB ripple level. The coupled line type low-pass filter with stripline configuration was fabricated by using a high-temperature superconducting (HTS ; $YBa_2Cu_3O_{7-x}$) thin film on MgO(100) substrate. Since the HTS coupled line type low-pass filter was proposed with five attenuation poles in stop band such as 1.8, 2.5, 4, 5.5, 62 GHz. The fabricated low-pass filter has improved the attenuation characteristics up to seven times of the cutoff frequency Bemuse of good rejection of the spurious signals and harmonics, our low-pass filter is applicable to mobile base station systems such as cellular, personal communication systems and international mobile telecommunication(IMT)-2000 systems.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.193-196
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• 2000

A new type low-pass filter design method based on a coupled line and transmission line theory is proposed to suppress harmonics by attenuation poles in the stop band. The design formula are derived using the equivalent circuit of a coupled transmission line. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range and low insertion loss. The seventh-order low-pass filter designed by present method has a cutoff frequency of 0.9 CHz with a 0.01 dB ripple level. The coupled line type low-pass filter with strip line configuration was fabricated by using a high-temperature superconducting (HTS : YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin film on MgO(100) substrate. Since the HTS coupled tine type low-pass filter was proposed with five attenuation poles in stop band such as 1.8, 2.5, 4, 5.5, 6.2 GHz. The fabricated low-pass filter has improved the attenuation characteristics up to seven times of the cutoff frequency.

• 한국전자파학회논문지
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• 제18권7호
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• pp.834-838
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• 2007

본 논문에서는 DGS 사이의 거리를 좁힌 C-DGS(Coupled-Defected Ground Structure)를 제 안하고, 이를 이용하여 차단 특성이 향상된 BSF(Bandstop Filter)를 제안하였다. 제안된 C-DGS는 각 DGS가 가지고 있는 인덕턴스 성분에 자계 결합을 발생시켜, 주기적인 구조를 가진 DGS와 비교해서 차단 특성이 향상된다. 또한, 제안된 C-DGS를 기존 보고된 양면 BSF에 적용시킨 새로운 BSF를 제작 및 측정하였다. C-DGS를 이용한 BSF는 3.8 GHz에서 15.5 GHz의 -20 dB 저지 대역을 가지며, 차단 특성은 110.8 dB/GHz로 기존 양면 대역 저지 여파기와 비교해서 차단 특성을 7.6배 향상시켰다. 제안된 C-DGS는 DGS를 이용한 고성능 여파기 설계에서 유용하게 적용될 수 있을 것이다.

• 한국전자파학회논문지
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• 제18권9호
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• pp.1039-1046
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• 2007

본 논문에서는 부성 자계 결합을 이용한 C-DGS를 제안하고, 이를 이용하여 차단 특성이 향상된 대역 저지 여파기(Bandstop Filter: BSF)를 설계하였다. 제안된 C-DGS는 부성 자계 결합을 이용하기 위해서 DGS 사이의 거리를 좁힌 구조로 부성 자계 결합의 효과로 인하여 차단 특성이 크게 향상된다. C-DGS를 이용한 BSF는 기존 연구 보고된 양면 BSF의 DGS 및 변형된 마이크로스트립 사이의 거리를 좁힘으로써 DGS 사이에 부성 자계 결합을 발생시킨 구조로 차단 특성은 3단 구조에서 -64.3 dB/GHz, 5단 구조에서 -108 dB/GHz 가지며, $4{\sim}11.3$ GHz의 -10 dB 저지 대역을 가진다. 특히, Bragg 법칙의 최대 반사 조건을 만족하는 BSF의 3단 구조와 비교하여 차단 특성을 3.8배 향상시켰고 크기를 35.2 % 감소시켰으며, 5단 구조와 비교하여 차단 특성을 2.4배 향상시켰고 크기를 40 % 감소시켰다. 또한, C-DGS를 이용한 BSF를 이용하여 단일 게이트 혼합기를 설계하여 6.6 dB의 변환 이득을 가짐을 확인하였다.