• 한국ITS학회 논문지
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• 제12권6호
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• pp.37-43
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• 2013

본 논문에서는 SIR(Stepped Impedance Resonator) 구조를 이용한 초광대역(UWB:Ultra Wide Band) 개방형 스터브 대역통과 여파기를 제안한다. 제안한 개방형 스터브 대역통과 여파기는 초광대역을 구현하기 위해 스터브 위치에 SIR 구조를 적용하였으며 낮은 삽입손실을 갖는다. 제안된 대역통과 여파기의 대역폭은 중심 주파수 5.8GHz에서 103% 이고, 삽입 및 반사손실은 각각 0.17dB 및 13.1dB이며 전체의 크기는$21.6{\times}17.8mm^2$ 이다.

• Current Optics and Photonics
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• 제4권1호
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• pp.69-80
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• 2020

A Rayleigh Lidar used for wind detection works by transmitting laser pulses to the atmosphere and receiving backscattering signals from molecules. Because of the weak backscattering signals, a lidar usually uses a high sensitivity photomultiplier as detector and photon counting technology for signal collection. The capturing of returned extremely weak backscattering signals requires the lidar to work on dark background with a long time accumulation to get high signal-to-noise ratio (SNR). Because of the strong solar background during the day, the SNR of lidar during daytime is much lower than that during nighttime, the altitude and accuracy of detection are also restricted greatly. Therefore this article describes an ultra-narrow bandwidth filter (UNBF) that has been developed on 354.7 nm wavelength of laser. The UNBF is used for suppressing the strong solar background that degrades the performance of Rayleigh wind lidar during daytime. The optical structure of UNBF consists of an interference filter (IF), a low resolution Fabry-Perot interferometer (FPI) and a high resolution FPI. The parameters of each optical component of the UNBF are presented in this article. The transmission curve of the aligned UNBF is measured with a tunable laser. Contrasting the result of with-UNBF and with-IF shows that the solar background received by a Licel transient recorder decreases by 50~100 times and that the SNR with-UNBF was improved by 3 times in the altitude range (35 km to 40 km) compared to with-IF at 10:26 to 10:38 on August 29, 2018. By the SNR comparison at four different times of one day, the ratio-values are larger than 1 over the altitude range (25~50 km) in general, the results illustrate that the SNR with-UNBF is better than that with-IF for Rayleigh Lidar during daytime and they demonstrate the effective improvements of solar background restriction of UNBF.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.7-12
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• 2005

A compact microstrip band-selective filter for ultra-wideband (UWB) radio system is proposed. The filter combines the traditional short-circuited stub highpass filter and coupled resonator bandstop filter on both sides of the mitered 50-ohm microstrip line. To realize the pseudo-highpass filtering characteristic over UWB frequency band (3.1 GHz to 10.6 GHz), a distributed highpass filter scheme is adopted. Three coupled resonators are utilized to obtain the band stop function at the desired frequency band. By meandering the coupled resonators, there is 29% reduction in footprint compared to the traditional bandstop filter using L-shaped resonators. The measured results show that the filter has a wide passband of 146.7 % (2.1 GHz to 10.15 GHz) with low insertion loss and the stop band of 7.42 % (5.32 GHz to 5.73 GHz) for 3-dB bandwidth. The measured group delay is less than 0.7 ns within the passband except the rejection band.

• 한국전자파학회논문지
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• 제18권7호
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• pp.704-709
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• 2007

본 논문에서는 UWB 시스템에 적용하기 위한 CPW 대역 통과 여파기를 제안하였다. 제안된 여파기는 특성 임피던스 $50{\Omega}$을 갖는 전송 선로에 슬롯만을 형성하여 대역 통과 특성을 갖도록 구현하였다. 설계된 대역 통과 여파기는 무선 랜 주파수 대역에서의 협대역 저지 특성을 얻기 위해 CPW 접지면에 두 쌍의 반파장 슬롯 공진기를 이용한 대역 저지 여파기와 결합하였다. 제작된 대역 통과 여파기는 $15.35{\times}13.60mm$의 작은 크기로 주파수 통과 대역은 3-dB 삽입 손실을 기준으로 $2.8{\sim}9.8GHz$이며 $5.15{\sim}5.71GHz$의 협대역 저지 대역을 갖는다. 또한, 군 지연 특성은 저지대역을 제외한 통과 대역 내에서 400 psec 이하를 나타낸다.

• Journal of electromagnetic engineering and science
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• 제18권3호
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• pp.188-198
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• 2018

In this study, we propose an approach for the design and satisfy the requirements of the fabrication of a small, lightweight, reliable, and stable ultra-wideband receiver for millimeter-wave bands and the contents of the approach. In this paper, we designed and fabricated a stable receiver with having low noise figure, flat gain characteristics, and low noise characteristics, suitable for millimeter-wave bands. The method uses the chip-and-wire process for the assembly and operation of a bare MMIC device. In order to compensate for the mismatch between the components used in the receiver, an amplifier, mixer, multiplier, and filter suitable for wideband frequency characteristics were designed and applied to the receiver. To improve the low frequency and narrow bandwidth of existing products, mathematical modeling of the wideband receiver was performed and based on this spurious signals generated from complex local oscillation signals were designed so as not to affect the RF path. In the ultra-wideband receiver, the gain was between 22.2 dB and 28.5 dB at Band A (input frequency, 18-26 GHz) with a flatness of approximately 6.3 dB, while the gain was between 21.9 dB and 26.0 dB at Band B (input frequency, 26-40 GHz) with a flatness of approximately 4.1 dB. The measured value of the noise figure at Band A was 7.92 dB and the maximum value of noise figure, measured at Band B was 8.58 dB. The leakage signal of the local oscillator (LO) was -97.3 dBm and -90 dBm at the 33 GHz and 44 GHz path, respectively. Measurement was made at the 15 GHz IF output of band A (LO, 33 GHz) and the suppression characteristic obtained through the measurement was approximately 30 dBc.

• 한국전자파학회논문지
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• 제21권1호
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• pp.28-35
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• 2010

분산 소자로 이루어진 고역 통과 필터의 최적화된 응답을 이용하여 우수한 차단 대역 특성과 통과 대역 내에 저지 대역을 갖는 UWB 대역 통과 필터를 설계 제작하였다. 변형된 고역 통과 필터의 등가 회로를 분산 소자로 구성하고, 최적화를 통해 FBW 100 % 이상의 넓은 통과 대역을 갖도록 하였다. Desegmentation technique로 급전선로간의 커플링 효과를 분석하고, 이를 이용하여 통과 대역 상, 하측의 우수한 차단 특성을 구현하였다. 또한, 최근 문제가 되고 있는 Wireless LAN과 Hyper LAN 대역(5.15~5.825 GHz)에서의 간섭 문제 해결을 위해, spurline을 추가하여 대역 저지를 실현하였다. 제작된 필터는 3.1~10.55 GHz의 통과 대역과 0.94 ns 이하의 평탄한 군 지연 응답을 보였고, 통과 대역 양단의 우수한 차단 대역과 5.2~6.12 GHz의 저지 대역이 측정되었다.

• Journal of Communications and Networks
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• 제17권6호
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• pp.622-633
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• 2015

The coexistence among different systems is a major problem in communications. Mutual interference between different systems should be analyzed and mitigated before their deployment. The paper focuses on two aspects that have an impact on the system performance. First, the coexistence analysis, i.e. evaluating the mutual interference. Second aspect is the coexistence techniques, i.e. appropriate system modifications that guarantee the simultaneous use of the spectrum by different technologies. In particular, the coexistence problem is analyzed between ultra-wide bandwidth (UWB) and narrow bandwidth (NB) systems emphasizing the role of spectrum sensing to identify and classify the NB interferers that mostly affect the performance of UWB system. A direct sequence (DS)-time hopping (TH) code design technique is used to mitigate the identified NB interference. Due to the severe effect of Narrowband Interference on UWB communications, we propose an UWB transceiver that utilizes spectrum-sensing techniques together with mitigation techniques. The proposed transceiver improves both the UWB and NB systems performance by adaptively reducing the mutual interference. Detection and avoidance method is used where spectrum is sensed every time duration to detect the NB interferer's frequency location and power avoiding it's effect by using the appropriate mitigation technique. Two scenarios are presented to identify, classify, and mitigate NB interferers.