• Journal of electromagnetic engineering and science
• /
• 제11권2호
• /
• pp.83-90
• /
• 2011

In this paper, we present the design method for a low-pass type inverter, which can effectively suppress the spurious response associated with band-pass filters. The inverter has a length of ${\lambda}/4$ and employs not only a stepped-impedance configuration but also asymmetrical and bending structures in order to improve frequency selectivity and compactness. The inverter is applied as an impedance/admittance inverter to the ultra-wideband (UWB) band-pass filter. The UWB band-pass filter configuration is based on a stub band-pass filter consisting of quarter-wavelength impedance inverters and shunt short-circuited stubs ${\lambda}/4$ in length. The asymmetrical stepped-impedance low-pass type inverter improves not only the spurious responses, but also the return loss characteristics associated with a UWB band-pass filter, while a compact size is maintained. The UWB band-pass filter using the proposed inverters is fabricated and tested. The measured results show excellent attenuation characteristics at out-band frequencies, which exceed 18 dB up to 39 GHz. The insertion loss within the pass-band (from 3.1 to 10.6 GHz) is below 1.7 dB, the return loss is below 10 dB, and the group delay is below 1 ns.

• E2M - 전기 전자와 첨단 소재
• /
• 제7권6호
• /
• pp.490-495
• /
• 1994

We investigated photoreflectance of semi-insulating GaAs with respect to modulation sources, that is, modulation beam intensity, modulation frequency, temperature, and thickness of sample. PR spectra by each modulation source turned out to be signals of low electric field third differential, and band gap values of sample were fitted by least square root method for Aspnes' theoretical equation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
• /
• pp.275-278
• /
• 2003

The aim of the study is to scrutinize the relationship between the area of resonance and center frequency with varying thickness by analyzing the characteristics of 2-port resonator. This was done through ideal design using Leach model equivalent model modified Mason model equivalent circuit for the application of bandpass filter high-frequency band with resonator Moreover, through the design of ladder-type BPF, we were able to observe changes in bandwidth, resonation, out-of-band rejection depending on the number and area of resonator.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
• /
• pp.838-841
• /
• 2003

The aim of the study is to scrutinize the relationship between the area of resonance and insertion loss by analyzing the characteristics of 2-port resonator. This was done through designing an air-gap type Film Bulk Acoustic Resonator (FBAR) by using CAD model for the application of bandpass filter of high-frequency band with piezoelectric thin film. Moreover, through the design of ladder-type BPF, we were able to observe changes in bandwidth, resonation, out-of-band rejection depending on the number and area of resonator.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2013년도 하계학술대회
• /
• pp.344-347
• /
• 2013

본 고에서는 AM과 FM라디오의 디지털방송 전환을 위하여 현재 사용 중인 방송대역에서의 IN-BAND 방식 외에도 VHF 하위대역 혹은 VHF상위대역을 사용하는 OUT-Of-BAND 방식에 대해 각 전송방식의 장단점을 분석하였다. 그러나 현재 디지털라디오뿐만 아니라 TV도 UHDTV 도입을 위해 VHF상위대역 주파수 사용을 원하고 있어 DMB와 라디오와 TV의 차세대방송 주파수 요구가 상호 충돌이 예상된다. 그러므로 본 고에서는 FM의 디지털라디오 전환방법으로 VHF하위대역(TV채널 5번과 6번)에서의 OUT-Of-BAND 방법에 의한 DRM+ 전송방식 적용을 제안하고 있다, 중파라디오의 디지털방송도 동일 계열 DRM 기술 적용으로 수신기를 값싸게 제조하고 빠르게 보급함으로써 디지털라디오의 활성화 방안을 제시하고 있다.

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

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
• /
• pp.265-268
• /
• 2003

In this paper, we introduce the SIR typed bandpass filters in CPW structures for shifting spurious harmonic frequency into higher frequency band. And we proposed the effective feed structures for suppressing spurious frequency in the SIR typed CPW bandpass filters. The designed folded feed structures have lowpass filtering characteristic. They are very effective feed types in the CPW bandpass filters for suppressing harmonics. The measured results of the CPW bandpass filter with folded feed line shows that it has suppressed and wide out-of-band up to 5.8fo.

• 한국군사과학기술학회지
• /
• 제22권4호
• /
• pp.475-483
• /
• 2019

Although radar target signatures(RTS), such as range profiles have played an important role for target recognition in the X-band radar, they would be less effective when a target is designed to have low radar cross section(RCS). Recently, a number of research groups have conducted the studies on the RTS in the VHF-band where such targets can be better detected than in the X-band. However, there is a lack of work carried out on the mathematical description of the VHF-band RTS. In this paper, chirplet decomposition is employed for modeling of the VHF-band RTS and its performance is compared with that of existing scattering center model generally used for the X-band. In addition, the discriminative signal analysis is performed by chirplet parameterization of range profiles from in an ISAR image. Because the chirplet decomposition takes long computation time, its fast form is further proposed for enhanced practicality.

• Journal of Chest Surgery
• /
• 제11권1호
• /
• pp.65-68
• /
• 1978

The unusual congenital anomaly, double chambered right ventricle due to aberrant muscle band with intact ventricular septum in 10 years old female patient is presented. The pressure gradient is 70mmHg between inflow tract and outflow tract of right ventricle and the aberrant muscle band is 2X4.5cm arising below the infundibulum and traverses the right ventricular cavity, extending from its anterior wall to the crista supraventricularis forming broad triangular base in parietal anterior wall. By resecting out this muscle band clearly, the outflow tract obstruction is completely relieved.

• 대한전자공학회논문지SD
• /
• 제41권8호
• /
• pp.51-57
• /
• 2004

Cascaded FBG(fiber Bragg grating)의 1차 분산과 2차 분산을 해석한 뒤 cascaded FBG의 2차 분산이 WDM/SCM (wavelength division multiplexing/subcarrier multiplexing) 시스템에서 발생한 왜곡 성분에 미치는 영향에 대하여 분석하였다. 아날로그 CATV의 최대 허용 왜곡 레벨인 IM₂ < -60 dBc, IM₃ <-95 dBc를 적용하여 최대 허용 왜곡 레벨에 도달하게 되는 값을 구하였고, 이 값을 통하여 왜곡의 허용 레벨 아래를 유지하기 위한 조건들을 제시하였다. Cascaded FBG-OADM을 사용한 WDM/SCM 시스템에서 공통주파수가 600 MHz, 광파장의 채널 간격이 50 GHz인 경우 FBG.의 3dB 반사 대역폭은 채널간격의 18 % 미만이 되어야 하며, 동일 조건에서 직접 변조 방식인 경우 18 %, 외부 변조 방식인 경우 70 % 미만이 되어야 한다는 제한을 받았다. 채널 간격이 50 GHz인 경우 공통주파수는 310 MHz 미만이 되어야 하며, FBG의 길이가 8 m인 경우 2차 혼변조 왜곡이 20 dB 이상 증가하였다.