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4축 구조를 사용한 4G 겸용 5G 이동통신용 빔 방향탐지 및 빔포밍 시스템
조규남,윤원상,채상훈 한국정보기술학회 2022 한국정보기술학회논문지 Vol.20 No.8
In this study, a directional antenna system for 4G and 5G mobile communication that can simultaneously perform beam direction finding and beamforming without using a motor was implemented. Active beam direction finding and beamforming of 5G signals is accomplished by an array-type directional antenna with 4 axes. In order to send a lot of RF signal to many users, the beam direction finding algorithm is applied to the receiver. In the transmitter, the beamforming method was used by adjusting the RF signal power applied to the two adjacent axes within the range of 0~31.5 dBm by an attenuator. As a result of experimenting with manufacturing a 4-axis array antenna system, beam direction finding was possible with a resolution of about 10°, and it was confirmed that 0~90° beamforming was possible with a resolution of about 10°. 본 연구에서는 모터를 사용하지 않고 빔 방향탐지와 빔포밍을 동시에 할 수 있는 4G 겸용 5G 이동통신용 지향성 안테나 시스템을 구현하였다. 5G 신호의 능동적인 빔 방향탐지와 빔포밍은 4개의 축을 갖는 어레이 형태의 지향성 안테나에 의해 이루어진다. 사용자가 많은 방향으로 전파를 많이 보내기 위하여 수신부에는 빔 방향탐지 알고리즘 적용하였으며, 송신부에는 이웃한 두 축 방향으로 가해지는 신호 전력을 감쇠기에 의해 0~31.5dBm 범위 내에서 각각 조절하여 빔포밍을 하는 방법을 사용하였다. 4축 어레이 안테나 시스템을 제작하여 실험해 본 결과 10° 정도의 해상력으로 빔 방향탐지가 가능하였으며, 이웃한 2축에 대하여 0~31.5dBm 범위로 각각 RF 신호를 감쇠시킬 때 10°의 해상력으로 0~90° 빔포밍이 가능한 것을 확인하였다.
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이승대(Lee, Seung-Dae),신현용(Shin, Hyun-Yong) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.5
본 논문에서는 수동소자를 이용한 필터 설계기술을 기반으로 하고 디지털 계단형 감쇠기를 이용하여 전력레벨 조절 이 가능한 주파수 상향 변환기를 설계 및 제작하였다.제작한 주파수 변환기는 저전력 및 저가의 제작비용을 실현하였으며 전력레벨의 조절이 가능하여 광범위한 영역에서 사용이 가능하다.실험 결과,중심 주파수 1,200MHz에서 160MHz의 대역을 확보하였으며 이득은 평균 0.75dB임을 확인하였다.또한,디지털 감쇠기를 통해 전력레벨을 10∼-21.5dBm까지 조절이 가능 함을 확인하였다. This paper suggests a power level controllable frequency up-converter which is designed and fabricated using both the filtering technology consisted with only passive devices and a multi-level digital attenuator. The suggested frequency up-converter simultaneously realizes the low power consumption and the low cost model. Because of the possibility for controlling power levels, it is possible to use the suggested frequency up-converter for wide spectral range. According to the experimental results, the average gain value of 0.75dB is obtained for the bandwidth of 160MHz at the center frequency of 1,200MHz. Especially, it is confirmed that the power level can be controlled from 10 to ?21.5dBm through the digital attenuator.
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RF 전력제한기용 실리콘 PIN 다이오드 패키지의 열적 거동 분석
백문철,김예빛,권봉준,조성배,정인용,하재권 한국물리학회 2023 새물리 Vol.73 No.6
In this study, we characterized the thermal behavior of a silicon PIN diode package used for a radio-frequency (RF) power limiter. The PIN diode was fabricated using a silicon process and designed to have a breakdown voltage of 250 V. A sequence of five RF pulses with a frequency of 2.7 GHz and a pulse width of 200 μs entered into the RF power limiter circuit, and the output power was measured. Then, the reflected and absorbed powers were respectively obtained using the scattering parameter (S-parameter) matrix. The absorption power proportion showed a slight decrease from 35% to 21.6% as the input power increased. Heat generation and temperature changes in the PIN diode package were analyzed by setting up a simple model and compared with the values actually measured by an infrared thermometer. The peak temperatures of the PIN diode package due to the heat absorbed by the RF pulses showed an almost linear increase when the RF input power increased from 30 to 59 dBm (1 to 810 W). The values calculated by the model matched well with the actual, measured ones within the error range. The temperature profiles of the package caused by input RF pulses were determined using the thermal time constant of the package material and showed a good match when the thermal time constant value was 3.2 ms.
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Chan Rok Park,Youngjin Lee,Hyungjin Yang 한국자기학회 2018 Journal of Magnetics Vol.23 No.3
The present study aims to confirm the attenuation correction (AC) in positron emission tomography (PET) images using various magnetic resonance (MR) sequences with and without the MR breast radiofrequency(RF) coil, and thus to evaluate the attenuation effect of the MR breast RF coil. To that purpose, we reconstructed non-attenuated PET data using the MR ACDixon-CAIPI, MR ACUTE, and MR ACDixon-GRAPPA sequences. The results indicated that the signal loss of the PET image with the MR breast RF coil was the lowest when the MR ACDixon-GRAPPA sequence was applied. In conclusion, the MR ACDixon-GRAPPA sequence maintained PET image quality when using the MR breast RF coil during PET/MR scanning.
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Wear-Induced Attenuation on Transmission Lines and Their Causes
Philipp Lenz,Philipp Baron,Armin Wittmann,Georg Fischer 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.1
In this paper, the radio frequency (RF) behavior of mechanically stressed coaxial and for the first time also twisted-pair transmission lines is investigated over their service life. The main goal is to enable predictive maintenance for cables in moving applications and avoid preventive replacement. This also reduces the use of high-cost resources. For this purpose, stranded and solid-core variants of coaxial and twisted-pair type cables are mechanically loaded on the two-pulley apparatus according to EN 50396. Their RF transmission (S21) behavior is measured using a vector network analyzer and presented over bending cycles. For the first time, the phase response of mechanically loaded transmission lines is evaluated with respect to their service life. Two significant causes for the increasing attenuation and altered phase response are identified: breakage in foil screen and increasing surface roughness on the copper conductors. The identified causes are supported with literature evidence. Through measurements and theoretical calculations, it is proven that the phase is much more suitable for an assessment of the remaining service life than the amplitude. The findings can be used to implement a cable monitoring system in industrial environments which monitors the lines in-situ and reminds the user to replace them, whenever a certain wear-level is reached.
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