• ETRI Journal
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• 제33권2호
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• pp.291-294
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• 2011

This letter proposes an open-ended waveguide antenna with a single split-ring resonator. In contrast to the waveguide antennas incorporating multiple rings reported in a previous study, which exhibited narrow bandwidth, the proposed antenna uses only one ring to achieve broader bandwidth while keeping the aperture small. A single ring has a relatively low quality factor compared to multiple rings. The simulated and measured fractional bandwidth was 4.13% and 4.03%, respectively, which is much broader than the fractional bandwidth of about 1% demonstrated in a previous study. This simple technique can be used in many applications that require small apertures including near-field probes and array elements.

• ETRI Journal
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• 제27권5호
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• pp.484-490
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• 2005

We fabricated 40 Gb/s front-end optical receivers using spot-size converter integrated waveguide photodiodes (SSC-WGPDs). The fabricated SSC-WGPD chips showed a high responsivity of approximately 0.8 A/W and a 3 dB bandwidth of approximately 40 GHz. A selective wet-etching method was first adopted to realize the required width and depth of a tapered waveguide. Two types of electrical pre-amplifier chips were used in our study. One has higher gain and the other has a broader bandwidth. The 3 dB bandwidths of the higher gain and broader bandwidth modules were about 32 and 42 GHz, respectively. Clear 40 Gb/s non-return-to-zero (NRZ) eye diagrams showed good system applicability of these modules.

• 한국전기전자재료학회논문지
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• 제14권9호
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• pp.744-750
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• 2001

Higher directivity acoustic transducer using the self-demodulation effect was fabricated. The structure of transducer was designed such as dimension and support type of the piezoelectric element, the vibrating metal plate, and the housing case. Based on the design, the transducer was fabricated and measured its acoustic characteristics. Also, AM modulated driving circuit was designed for using the self-demodulation effect. The piezoelectric sounder with 200kHz resonant frequency and 20kHz bandwidth was designed by considering the sharp directivity and the sound pressure. The design and fabrication method worked in this study can be utilized in development of various speakers with higher directivity and broader bandwidth.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.255-258
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• 2005

In this paper, we verify that the bandwidth of the optimized disk-loaded monopole antenna with electromagnetically coupled feed obtained using a genetic algorithm is broader than the theoretical bandwidth limit of 2/Q by simulation as well as by measurement. The measured bandwidth of the optimized antenna (kr : 0.599) is about 42% from 380 MHz to 580 MHz (VSWR<5.8). The efficiency measurement of the antenna is over 90% for the frequency band of operation.

• 대한전자공학회논문지TC
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• 제38권6호
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• pp.18-27
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• 2001

본 논문에서는 변형된 MSA에 전기력선의 제한이 없도록 용량을 장하한 MSA를 제안했다. 제안된 안테나는 1.9 GHz의 중심 주파수에서 7.76%의 대역폭을 갖고, 임의의 급전점 변화에 따라 대역폭과 공진주파수의 변화를 보였다. 용량을 장하한 MSA는 변형된 MSA보다 개선된 대역폭을 얻었다. 전송 선로 모델의 안테나 등가 회로는 정확한 공진 주파수를 찾기 위해 설계되었고, return loss 값을 계산했다. 계산된 값은 실험값과 양호하게 일치되었다.

• Journal of electromagnetic engineering and science
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• 제18권1호
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• pp.1-6
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• 2018

In this study, the analytic expression for the positive/negative $n^{th}-Mode$ resonance frequency of an N unit cell composite right-/lefthanded (CRLH) transmission line is derived. To explain the resonance mechanism of the $n^{th}$ mode, especially for the negative mode, the current distribution of the N unit cell CRLH transmission line is investigated with a circuit simulation. Results show that both positive and negative $n^{th}$ resonance modes have n times current variations, but their phase difference is $180^{\circ}$ as expected. Moreover, the positive $n^{th}$ resonance occurs at a high frequency, whereas the negative $n^{th}$ resonance transpires at a low frequency, thus indicating that the negative resonance mode can be utilized for a small resonator. The correlation between the slope of the dispersion curve and the bandwidth is also observed. In sum, the balanced condition of the CRLH transmission line provides a broader bandwidth than the unbalanced condition.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.127-128
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• 2006

In this paper, we propose a novel signaling method using chirp signals in UWB radio with satisfaction of FCC regulation. Chirp signals have been used in many ranging systems such as radar because of its good correlation properties. Because it is important to use broader signal bandwidth in order to get higher precision of the ranging, according to the Cramer-Rao Lower Bound, UWB radio is extremely good as the ranging systems. But, it is very difficult to apply existing chirp signals to UWB, because FCC regulates that the systems operating in UWB radio must occupy signal bandwidth more than 500MHz on the condition of stopping the frequency sweeping. So, we propose multiple chirp signals which can satisfy the regulation of FCC while maintaining chirp signal's properties. The multiple chirp signals which are composed of the sub-chirps modulated by sub-carriers can expand the signal bandwidth with the same principle of OFDM systems. The simulation results show that the BER performance of the proposed multiple chirp signals is identical to that of conventional OFDM when it is applied to data communication, and that the correlation properties of the proposed signals are almost the same with properties as those of single chirp signals whose sweeping bandwidth is the same value with the proposed one.

• 전자공학회지
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• 제25권4호
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• pp.14-26
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• 1998

Emergence of the Interned, World Wide Web (WWW), and multimedia services accelerates the demand for broadband access to mass market. As the demand for broader bandwidth for local access rapidly increases, new types of services for local access have been offered or are being developed. However, nothing has yet been shown up for a definite long-term solution. In this article, we address some issues and technological perspectives of such emerging local access demand.

• 한국전자파학회논문지
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• 제11권5호
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• pp.773-781
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• 2000

본 논문에서는 기존의 원형 링 마이크로스트립 슬롯 안테나의 협대역 특징을 개선하기 위해서 변형된 원형링 마이크로스트립 슬롯 안테나를 제안하였다. 제안된 안테나는 비대칭 슬롯을 가지며 일반적인 마이크로스트립 라인으로 급전하였다. 이 안테나를 시간 영역 유한 차분법(FDTD)을 이용하여 최적화 한 후, 제작.측정하였다. 논문에서 제안된 안테나는 VSWR<2를 기준으로 1 octave 이상의 광대역 특성을 얻을 수 있었으며, 이는 기존의 원형 링 마이크로스트립 슬롯 안테나의 단점인 협대역 특성을 같은 크기에서 획기적으로 개선한 것이다.

• 한국정보통신학회논문지
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• 제10권11호
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• pp.1940-1945
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• 2006

본 논문에서는 S밴드(24 GHz)와 C밴드(4-8 GHz)에서 사용가능한 비동심원 복사구조와 저 임피던스 급전구조를 갖는 소형 광대역 원형 링슬롯 안테나를 제안하였다. 본 안테나는 유전율 4.3, 두께 1mm의 기판을 대상으로 해석되었다. 제안된 안테나의 측정된 임피던스 대역폭은 $118%(S_{11}{\leq}-10dB)$이므로 기존의 원형 링슬롯 안테나보다 훨씬 광대역이다. 또한 주요 설계변수들을 변화시켰을 때 변경되는 안테나의 특성을 연구함으로써 최적화설계에 도움이 되도록 하였다.