• 전자공학회논문지T
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• 제36T권4호
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• pp.103-109
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• 1999

본 논문에서는 2-층의 유전체로 구성하여 한방향 복사특성을 갖는 T-모양 급전선의 슬롯 안테나인 새로운 구조를 제안하였다. 또한 양방향으로 복사특성을 갖는 슬롯 안테나는 한방향으로만 복사하기를 원할 경우, 반사판을 별도로 설치해야 한다. 그러나 여기에서 제시한 안테나는 별도의 반사판 설치가 필요없게 된다. T-모양의 마이크로스트립 급전 구조는 슬롯의 폭 변화에도 임피던스 정합이 쉽게 이룰 수 있었다. 그리고 슬롯 안테나의 대역폭은 슬롯 폭에 비례하여 확장되는 특성을 얻었다. 여기서 제시한 급전 구조는 방사저항이 낮은 값으로 일정하게 유지되어 슬롯 폭과 거의 무관한 좋은 특성을 얻었다. FDTD법으로 모델링하여 전계분포를 시간 영역에서 계산하였고, 이를 Fourier 변환시켜 슬롯 안테나의 반사손실, 전압 정재파비, 복사 패턴을 주파수 영역에서 계산하였다. 측정한 결과로부터, 대역폭은 중심 주파수 2.5GHz에서 약 34.8%의 광대역 특성을 보였다. 측정치들은 계산치들과 비교적 잘 일치하였다.

• 한국전자파학회논문지
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• 제20권4호
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• pp.323-332
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• 2009

본 논문에서는 기존의 $\lambda_0$/4 단락 스터브 대역 통과 필터의 특성을 개선하여 LTCC(Low Temperature Co-fired Ceramic)을 이용하여 UWB(Ultra Wideband) 응용에 적합한 필터 기술을 소개한다. 높은 유전 상수의 기판($\varepsilon_r$ = 40)상에 기존의$\lambda_0$/4의 단락 스터브 대역 통과 필터 기술을 적용하기 위하여 기존의 필터와는 다르게 낮은 특성 임피던스 선로를 이용하여 결과적으로 스터브의 수를 다섯 개에서 두 개로 감소시켰다. 또한, 3개의 단락 결합 선로를 이용해서 5.15 GHz에서 5.825 GHz의 주파수 범위에서 WLAN(Wireless Local Area Network) 저지 대역을 특성 내에 삽입하였다. 본 필터는 통과 대역에서 1 dB 미만의 삽입 손실과 10 dB 이상의 반사 손실을 갖는 것으로 측정되었고, 109.49 %의 대역폭 율이 달성되었다. 측정 결과는 시뮬레이션 결과와 잘 일치한다. 필터의 크기는 $4{\times}8{\times}0.57\;mm^3$이다.

• ETRI Journal
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• 제31권3호
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• pp.254-262
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• 2009

This paper presents a novel simple filter design method based on a parallel short-ended coupled-line structure with capacitive loading for size reduction and ultra-broad rejection of spurious passbands. In addition, the introduction of a cross-coupling capacitor into the miniaturized coupled-line can create a transmission zero at the second harmonic frequency for better frequency selectivity and attenuation level. The aperture compensation technique is also applied to achieve a strong coupling in the coupled-line section. The influence of using the connecting transmission line to cascade two identical one-stage filters is studied for the first time. Specifically, such a two-stage bandpass filter operating at 2.3 GHz with a fractional bandwidth of 10% was designed and realized with low-temperature co-fired ceramic technology for application in base stations that need high power handling capability. It achieved attenuation in excess of -40 dB up to $4f_0$ and low insertion loss of -1.2 dB with the size of 10 mm ${\times}$ 7 mm ${\times}$ 2.2 mm. The measured and simulated results showed good agreement.

• 한국전자파학회논문지
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• 제15권12호
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• pp.1141-1146
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• 2004

본 논문에서는 무궁화 3호 위성의 방송수신용 안테나를 설계 및 제작하였는데, 기존의 방송수신용 안테나보다 넓은 수신영역을 가지는 고이득 안테나를 제작하는데 중점을 두었다. 본 안테나는 급전 라인의 손실을 줄이기 위하여 급전 라인을 도파관 구조로 설계하였다. 또한 방사효율을 높이고 급전 구조를 간단히 하기 위하여 cavity backed slot array 형태의 방사구조를 제안하였다. 슬롯 배열 안테나의 최대 이득은 11.7 GHz$\~$12.75 GHz 대역에서 33 dEi 이상을 얻을 수 있었다. 임피던스 대역폭 또한 VSWR 2:1에서 $13\%$로 설계사양을 만족시켰다.

• Journal of Biosystems Engineering
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• 제25권2호
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• pp.97-106
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• 2000

To develop the grain moisture meter using microwave free space transmission technique, a 10.5GHz microwave signal with the power of 11mW generated by an oscillar with a dielectric resonator is transmitted to an isolator and radiated from a transmitting $2{\times}2$ microstrip patch array antenna into the sample holder filled with the 12 to 26%w.b. of Korean Hwawung paddy rice. the microwave signal, attenuated through the grain with moisture, is collected by a receiving $2{\times}2$ microstrip patch array antenna and detected using a Shottky diode with excellent high frequency characteristic. A pair of light and simple microstrip patch array antenna for measurement of grain moisture content is designed and implemented on atenflon substrate with trleative dielectric constant of 2.6 and thickness of 0.54 by using Ensemble ver. 4.02 software. The aperture of microstrip patch arrays is 41 mm width and 24mm high. The characteristics of microstrip patch antenna such as grain. return loss, and bandwidth are 11.35dBi, -38dB and 0.35GHz($50^{\circ}$ at far-field pattern of E and H plane. The width of the sample holder is large enough to cover the signal between the antennas temperature and bulk density respectively. The calibration model for measurement of grain moisture content is proposed to reduce the effects of fluectuations in bulk density and temperature which give serious errors for the measurements . From the results of regression analysis using the statistically analysis method, the moisture content of grain samples (MC(%)) is expressed in terms of the output voltage(v), temperature (t), and bulk density of samples(${\rho}b$)as follows ;$$MC(%)\;=\;(-3.9838{\times}10^{-8}{\times}v^{3}+8.023{\times}10^{-6}{\times}v^{2}-0.0011{\times}v-0.0004{\times}t+0.1706){\frac{1}{{\rho}b}}{\times}100$ Its determination coefficient, standard error of prediction(SEP) and bias were found to be 0.9855, 0.479%w.b. and -0.0.369 %w.b. respectively between measured and predicted moisture contents of the grain samples.

• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.238-243
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• 2010

CSD is Active RFID based Container Security Device which is proposed by the U.S Department of Home Security. It is mounted inside the container to sense opening of the container door. ConTracer is the CSD which is developed in this research whose major features are sensing door opening status as well as history inquiring on internal environment and shock to the container by mounting the temperature/ humidity/ shock sensors. Moreover, its RFID frequency bandwidth uses 433MHz and 2.4GHz to correspond actively to the frequency used by different countries. This paper introduces the development trend of CSD, compares the ConTracer which is developed thru this research and other company's CSD, and introduces CSD System which is designed and established using ConTracer. Finally, the implemented CSD System is verified by applying the demonstration service to container distribution between Korea and China.

• Current Optics and Photonics
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• 제5권4호
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• pp.384-390
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• 2021

This paper presents a wide-range tunable wavelength-locking technology based on optoelectronic oscillation (OEO) loops for optical fiber sensors and microwave photonics applications, explains the theoretical fundamentals of the design, and demonstrates a method for locking the relative wavelength differences between a leader semiconductor laser and its follower lasers. The input of the OEO loop in the proposed scheme (the relative wavelength difference) determines the radio-frequency (RF) signal frequency of the oscillation output, which is quantized into an injection current signal for feedback to control the wavelength drift of follower lasers so that they follow the wavelength change of the leader laser. The results from a 10-hour continuous experiment in a field environment show that the wavelength-locking accuracy reached ±0.38 GHz with an Allan deviation of 6.1 pm over 2 hours, and the wavelength jitter between the leader and follower lasers was suppressed within 0.01 nm, even though the test equipment was not isolated from vibrations and the temperature was not controlled. Moreover, the tunable range of wavelength locking was maintained from 10 to 17 nm for nonideal electrical devices with limited bandwidth.

• ETRI Journal
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• 제27권5호
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• pp.551-556
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• 2005

We have demonstrated a high-power widely tunable sampled grating distributed Bragg reflector (SGDBR) laser integrated monolithically with a semiconductor optical amplifier (SOA) having a lateral tapered waveguide, which is the first to emit a fiber-coupled output power of more than 10 dBm using a planar buried heterostructure (PBH). The output facet reflectivity of the integrated SOA using a lateral tapered waveguide and two-layer AR coating of $TiO_2\;and\;SiO_2$ was lower than $3\;{\times}\;10^{-4}\;over$ a wide bandwidth of 85 nm. The spectra of 40 channels spaced by 50 GHz within the tuning range of 33 nm were obtained by a precise control of SG and phase control currents. A side-mode suppression ratio of more than 35 dB was obtained in the whole tuning range. Fiber-coupled output power of more than 11 dBm and an output power variation of less than 1 dB were obtained for the whole tuning range.

• Journal of electromagnetic engineering and science
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• 제14권1호
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• pp.1-8
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• 2014

A differential-cascode CMOS power amplifier (PA) with a supply modulator for envelope tracking (ET) has been implemented by 0.18 ${\mu}m$ RF CMOS technology. The loss at the output is minimized by implementing the output transformer on a FR-4 printed circuit board (PCB). The CMOS PA utilizes the $2^{nd}$ harmonic short at the input to enhance the linearity. The measurement was done by the 10MHz bandwidth 16QAM 6.88 dB peak-to-average power ratio long-term evolution (LTE) signal at 1.85 GHz. The ET operation of the CMOS PA with the supply modulator enhances the power-added efficiency (PAE) by 2.5, to 10% over the stand-alone CMOS PA for the LTE signal. The ET PA achieves a PAE of 36.5% and an $ACLR_{E-UTRA}$ of -32.7 dBc at an average output power of 27 dBm.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권3호
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• pp.179-192
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• 2008

A multiphase compensation method with mismatch linearization technique, is presented and demonstrated in a $\Sigma-\Delta$ fractional-N frequency synthesizer. An on-chip delay-locked loop (DLL) and a proposed delay line structure are constructed to provide multiphase compensation on $\Sigma-\Delta$ quantizetion noise. In the delay line structure, dynamic element matching (DEM) techniques are employed for mismatch linearization. The proposed $\Sigma-\Delta$ fractional-N frequency synthesizer is fabricated in a $0.18-{\mu}m$ CMOS technology with 2.14-GHz output frequency and 4-Hz resolution. The die size is 0.92 mm$\times$1.15 mm, and it consumes 27.2 mW. In-band phase noise of -82 dBc/Hz at 10 kHz offset and out-of-band phase noise of -103 dBc/Hz at 1 MHz offset are measured with a loop bandwidth of 200 kHz. The settling time is shorter than $25{\mu}s$.