• Title, Summary, Keyword: RF(Radio Frequency)

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Simulation Method for Radio-Frequency Single-Electron Transistor (RF-SET) Operation (고주파 단일전자 트랜지스터 (RF-SET) 동작의 시뮬레이션 방법)

  • Yu Yun Seop;Park Hyun-Sik
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.42 no.5
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    • pp.9-14
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    • 2005
  • Simulation method for a pure radio-frequency (rf) mode of reflection-type and a pure rf mode of transmission-type radio-frequency single-electron transistor (RF-SET) operation is introduced. In this method, the solutions of differential equations based on Kirchhoff's law are obtained self-consistently at frequency-domain. Also, the steady-sate single-electron transistor (SET) current model and the time-dependent SET current model are used in this method. The reflected wave of a typical reflection-type RF-SET and the transmitted wave of a typical transmission-type RF-SET are calculated, and the accuracy of our developed method including the steady-state SET current model is verified with the method introduced by reference 2. At high frequency over GHz, results of our developed method including the time-dependent SET current model are considerably different from that including the steady-state SET current model. At high frequency over GHz, an exact time-dependent SET current model is needed to analyze RF-SET operation.

A Searching Algorithm for Minimum Bandpass Sampling Frequency in Simultaneous Down-Conversion of Multiple RF Signals

  • Bae, Jung-Hwa;Park, Jin-Woo
    • Journal of Communications and Networks
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    • v.10 no.1
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    • pp.55-62
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    • 2008
  • Bandpass sampling (BPS) techniques for the direct down-conversion of RF bandpass signals have become an essential technique for software defined radio (SDR), due to their advantage of minimizing the radio frequency (RF) front-end hardware dependency. This paper proposes an algorithm for finding the minimum BPS frequency for simultaneously down-converting multiple RF signals through full permutation over all the valid sampling ranges found for the multiple RF signals. We also present a scheme for reducing the computational complexity resulting from the large scale of the purmutation calculation involved in searching for the minimum BPS frequency. In addition, we investigate the BPS frequency allowing for the guard-band between adajacent down-converted signals, which help lessen the severe requirements in practical implementations. The performance of the proposed method is compared with those of other pre-reported methods to prove its effectiveness.

Filter design for protecting signal interference between RF equipments on aircraft (항공기 RF 장비들의 신호 간섭 방지를 위한 필터 설계)

  • Kim, Junhyoung;Kim, Bong-Gyu;Jeon, Young-Gu;Lee, Seong-Woo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.3
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    • pp.246-252
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    • 2013
  • This paper presents method to suppress signal interference by using the filter in the RF output stage of the radiation equipment as a way to avoid interference between the RF(Radio Frequency) equipment mounted on aircraft. Especially filter design to suppress harmonics of the radiation equipment and testing method to verify the filter's performance is presented. Filter was installed at RF output stage of U/VHF radio in order to prevent interference between U/VHF(Ultra/Very High Frequency) radio and data link system. Filter design and testing method in this paper will be able to give help in the design of aircraft equipments as a tool that can be used to establish measures for problem of interference in the aircraft.

Remote Impedance-based Loose Bolt Inspection Using a Radio-Frequency Active Sensing Node

  • Park, Seung-Hee;Yun, Chung-Bang;Inman, Daniel J.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.3
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    • pp.217-223
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    • 2007
  • This paper introduces an active sensing node using radio-frequency (RF) telemetry. This device has brought the traditional impedance-based structural health monitoring (SHM) technique to a new paradigm. The RF active sensing node consists of a miniaturized impedance measuring device (AD5933), a microcontroller (ATmega128L), and a radio frequency (RF) transmitter (XBee). A macro-fiber composite (MFC) patch interrogates a host structure by using a self-sensing technique of the miniaturized impedance measuring device. All the process including structural interrogation, data acquisition, signal processing, and damage diagnostic is being performed at the sensor location by the microcontroller. The RF transmitter is used to communicate the current status of the host structure. The feasibility of the proposed SHM strategy is verified through an experimental study inspecting loose bolts in a bolt-jointed aluminum structure.

Radio environment maps: The survey of construction methods

  • Pesko, Marko;Javornik, Tomaz;Kosir, Andrej;Stular, Mitja;Mohorcic, Mihael
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.11
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    • pp.3789-3809
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    • 2014
  • Radio environment maps (REMs) and geolocation database represent an important source of information for the operation of cognitive radio networks, replacing or complementing spectrum sensing information. This paper provides a survey of methods for constructing the radio frequency layer of radio environment map (RF-REM) using distributed measurements of the signal levels at a given frequency in space and time. The signal level measurements can be obtained from fixed or mobile devices capable of sensing radio environment and sending this information to the REM. The signal measurements are complemented with information already stored in different REM content layers. The combined information is applied for estimation of the RF-REM layer. The RF-REM construction methods are compared, and their advantages and disadvantages with respect to the spatial distribution of signal measurements and computational complexity is given. This survey also indicates possible directions of further research in indirect RF-REM construction methods. It emphasizes that accurate RF-REM construction methods should in the best case support operation with random and clustered signal measurements, their operation should not be affected by measurements outliers, and it must estimate signal levels comparably on all RF-REM locations with moderate computational effort.

Graphene field-effect transistor for radio-frequency applications : review

  • Moon, Jeong-Sun
    • Carbon letters
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    • v.13 no.1
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    • pp.17-22
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    • 2012
  • Currently, graphene is a topic of very active research in fields from science to potential applications. For various radio-frequency (RF) circuit applications including low-noise amplifiers, the unique ambipolar nature of graphene field-effect transistors can be utilized for high-performance frequency multipliers, mixers and high-speed radiometers. Potential integration of graphene on Silicon substrates with complementary metal-oxide-semiconductor compatibility would also benefit future RF systems. The future success of the RF circuit applications depends on vertical and lateral scaling of graphene metal-oxide-semiconductor field-effect transistors to minimize parasitics and improve gate modulation efficiency in the channel. In this paper, we highlight recent progress in graphene materials, devices, and circuits for RF applications. For passive RF applications, we show its transparent electromagnetic shielding in Ku-band and transparent antenna, where its success depends on quality of materials. We also attempt to discuss future applications and challenges of graphene.

Implementation of Radio Frequency Communication System based Serial UART Communication (직렬 UART 통신 기반 rf 통신 시스템 구현)

  • Jin, Hyun-Soo
    • Journal of Digital Convergence
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    • v.12 no.12
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    • pp.257-264
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    • 2014
  • Through MCU model, Radio Frequency communication is completed using universal asynchronous receiver and transmitter. The communicatin with PC and MCU is completed using RS-232 cable. At first interconnected communication with PC and MCU is necessary for RF communication because tha UART is based technique for RF communication. Program imbeded in microcontroller unit is ran during RF signal is transmitted to other RF module. Data connected with PC and MCU is transmitted between PC and MCU during PC and MCU is connected.

RF Band-Pass Sampling Frontend for Multiband Access CR/SDR Receiver

  • Kim, Hyung-Jung;Kim, Jin-Up;Kim, Jae-Hyung;Wang, Hongmei;Lee, In-Sung
    • ETRI Journal
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    • v.32 no.2
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    • pp.214-221
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    • 2010
  • Radio frequency (RF) subsampling can be used by radio receivers to directly down-convert and digitize RF signals. A goal of a cognitive radio/software defined ratio (CR/SDR) receiver design is to place the analog-to-digital converter (ADC) as near the antenna as possible. Based on this, a band-pass sampling (BPS) frontend for CR/SDR is proposed and verified. We present a receiver architecture based second-order BPS and signal processing techniques for a digital RF frontend. This paper is focused on the benefits of the second-order BPS architecture in spectrum sensing over a wide frequency band range and in multiband receiving without modification of the RF hardware. Methods to manipulate the spectra are described, and reconstruction filter designs are provided. On the basis of this concept, second-order BPS frontends for CR/SDR systems are designed and verified using a hardware platform.

RF Resonators Using Microstrip Transmission Line at 3 T MRI (3 T 자기공명영상시스템에서의 마이크로스트립을 이용한 다양한 RF 공진기)

  • Yoo, Hyoungsuk
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.5
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    • pp.663-666
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    • 2013
  • This paper demonstrates four different radio frequency (RF) resonators at 3 T magnetic resonance imaging (MRI) system. An approach based on microstrip transmission line to identical RF resonators except upper stripline structure is investigated. Electromagnetic simulation results are compared for RF resonators and discussed in detail at 3 T.

Determination of electron energy distribution functions in radio-frequency (RF) and microwave discharges (RF/마이크로웨이브 방전에서의 전자에너지 분포함수의 결정)

  • 고욱희;박인호;김남춘
    • Journal of the Korean Vacuum Society
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    • v.10 no.4
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    • pp.424-430
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    • 2001
  • An electron Boltzmann equation is solved numerically to calculate the electron energy distribution functions in plasma discharge which is generated by radio-frequency (RF) and microwave frequency electric field. The maintenance field strengths are determined self-consistently by solving the homogeneous electron Boltzmann equation in the Lorentz approximation expressed by 2nd order differential equation and an additional particle balance equation expressed by integro-differential equation. By using this numerical code, the electron energy distribution functions in argon discharge are calculated in the range from RF to microwave frequency. The influence of frequency of the HF electric field on the electron energy distribution functions and ionization rate are investigated.

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