• Title/Summary/Keyword: multiband

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Internal Monopole Antenna Design for Multiband Operation and SAR Analysis (내장형 모노폴 안테나 설계 및 SAR분석)

  • Shin Chan-Soo;Shin Ho-Sub;Kim Nam;Choi Jae-Ic;Park Ju-Derk
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.12 s.91
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    • pp.1190-1198
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    • 2004
  • In this paper, meander-line planar monopole antenna mounted on PCS/IMT-2000/WLAN handset for SAR reduction is designed. Frequency characteristics and SAR value optimized with various design parameters are analyzed and designed. Designed internal monopole antenna mounted on the handset is simulated. The 1 g and 10 g peak average SARs of internal monopole antenna are 0.656 and 0.387 W/kg respectively. And internal monopole antenna and external monopole antenna attached on the handset are tested. As a result, internal monopole antenna 1 g and 10 g peak average SARs are 0.686 and 0.356 W/kg. And external monopole antenna's results are 1.33 and 0.812 W/kg, respectively. So internal monopole antenna has a about $50\%$ SAR reduction in comparison with external monopole antenna.

DEEP-South: The Progress Report

  • Moon, Hong-Kyu;Kim, Myung-Jin;Park, Jintae;JeongAhn, Youngmin;Yang, Hongu;Lee, Hee-Jae;Kim, Dong-Heun;Roh, Dong-Goo;Choi, Young-Jun;Yim, Hong-Suh;Lee, Sang-Min;Kwak, SungWon
    • The Bulletin of The Korean Astronomical Society
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    • v.43 no.1
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    • pp.42.1-42.1
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    • 2018
  • Deep Ecliptic Patrol of the Southern Sky (DEEP-South) observation is being made during the off-season for exoplanet survey, using Korea Microlensing Telescope Network (KMTNet). An optimal combination of its prime focus optics and the 0.3 billion pixel CCD provides a four square degrees field of view with 0.4 arcsec/pixel plate scale which is also best suited for small body studies. Normal operation of KMTNet started in October 2015, and a significant portion of the allocated telescope time for DEEP-South is dedicated to targeted observation, Opposition Census (OC), of near-Earth asteroids for physical and taxonomic characterization. This is effectively achieved through multiband, time series photometry using Johnson-Cousins BVRI filters. Uninterrupted monitoring of the southern sky with KMTNet is optimized for spin characterization of a broad spectrum of asteroids ranging from the near-Earth space to the main-belt, including binaries, asteroids with satellites, slow/fast- and non-principal axis-rotators, and thus is expected to facilitate the debiasing of previously reported lightcurve observations. Our software subsystem consists of an automated observation scheduler, a pipelined data processing system for differential photometry, and an easy-to-use lightcurve analysis toolkit. Lightcurves, spin periods and provisional determination of class of asteroids to which the lightcurve belongs will be presented, using the dataset from first year operation of KMTNet. Our new taxonomic classification scheme for asteroids will also be summarized.

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A Study on dual-band Wilkinson power divider with ${\pi}$-shaped parallel stub transmission lines for WLAN (${\pi}$-형 병렬 스터브 전송선로를 이용한 WLAN용 이중대역 Wilkinson 전력 분배기에 대한 연구)

  • Jo, Won-Geun;Kim, Dong-Seek;Ha, Dong-Ik;Cho, Hyung-Rae
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.9 no.6
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    • pp.105-112
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    • 2010
  • Recently, wireless communication systems have been developed and the circuits which operate with the broad-band for multiband uses were introduced. However, broad-band circuits have problems that inevitably increase the size. Dual-band circuit operates only two frequency, therefore, it will be able to miniaturize through unnecessary decreased elements. The Wilkinson power divider is the one of the most commonly used components in wireless communication system for power division. Nowaday, the Wilkinson power divider is also demanded dual-band. In this paper, I propose miniaturized dual-band Wilkinson power divider operating at 2.45 GHz and 5.2 GHz for IEEE 802.11n standard. Proposed dual-band Wilkinson power divider is used in parallel stub line. The design is accomplished by transforming the electrical length and impedance of the quarter wave sections of the conventional Wilkinson power divider into dual band ${\pi}$-shaped sections.

Design of CMOS LC VCO with Linearized Gain for 5.8GHz/5.2GHz/2.4GHz WLAN Applications (5.8GHz/5.2GHz/2.4GHz 무선 랜 응용을 위한 선형 이득 CMOS LC VCO의 설계)

  • Ahn Tae-Won;Moon Yong
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.42 no.6 s.336
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    • pp.59-66
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    • 2005
  • CMOS LC VCO for tri-bind wireless LAN applications was designed in 1.8V 0.18$\mu$m CMOS process. PMOS transistors were chosen for VCO core to reduce flicker noise. The possible operation was verified for 5.8GHz band (5.725$\~$5.825GHz), 5.2GHz band (5.150$\~$5.325GHz), and 2.4GHz band (2.412$\~$2.484GHz) using the switchable L-C resonators. To linearize its frequency-voltage gain (Kvco), optimized multiple MOS varactor biasing technique was used for capacitance linearization and PLL stability improvement. VCO core consumed 2mA current and $570{\mu}m{\times}600{\mu}m$ die area. The phase noise was lower than -110dBc/Hz at 1MHz offset for tri-band frequencies.

A Dual-Sprial Line Loaded Monopole Antenna having a Vertical Groundplane for Quadband Applications (수직 접지면을 가지는 4중 대역용 이중 스파이럴 라인 로디드 모노폴 안테나)

  • Kim, Byoung-Chul;Nguyen, Truong Khang;Choo, Ho-Sung;Park, Ik-Mo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.8
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    • pp.899-905
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    • 2008
  • In this paper, we propose a dual-spiral line loaded monopole antenna having a vertical ground plane for quadband applications. The antenna occupies a volume of $38{\times}12{\times}7\;mm^3$ with a $40{\times}92\;mm^2$ ground plane. The measured impedance bandwidths of the antenna based on $VSWR{\le}2$ are approximately of 11.7 % and 24.8 % in the first and second frequency band, respectively. The operating frequency can simultaneously cover Cellular($0.824{\sim}0.894\;GHz$), PCS($1.750{\sim}1.870\;MHz$), UMTS($1.920{\sim}2.170\;MHz$), and IMT-2000($1.885{\sim}2.200\;GHz$) bands. The maximum gains of the antenna are -0.99 dBi, 4.07 dBi, 2.72 dBi, and 4.33 dBi at the center frequencies of the Cellular, PCS, UMTS, and IMT-2000 bands, respectively. Good radiation patterns are experimentally obtained.

A study on the implementation and performance evaluation of low-power ZigBee sensor in the M2M gateway system (M2M Gateway 시스템을 위한 저전력 지그비 센서 구현 및 성능평가에 관한 연구)

  • Jeon, Joong-Sung;Kim, Nam-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.7
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    • pp.629-634
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    • 2016
  • This paper describes the implementation of a ZigBee sensor node that can be utilized as a multiband and machine to machine (M2M) communication gateway. The IEEE 802.15.4-2003 standard was used as the wireless network frequency band. Ember's Type EM357 SoC was used as the transmission and reception device to perform the communication function, and it was also used for both the main M2M gateway and the sensor node. For the implementation of the operating protocol, EmberZNet Stack 4.5.4 from the Ember Corporation was used. The measurement of the reception sensitivity in the receiving module and the actual output signal from the reference were obtained from the transmission of a packet, and the packet included the M2M gateway within the attached ZigBee sensor. The packet error rate was measured as 0% with a -98 dBm reception sensitivity at the ZigBee frequency. In addition, excellent current characteristics of the ZigBee modules were shown by the implementation of the low-power circuit.

Adaptive Dual-Hop Transmission Based On Hierarchical Modulation in UWB System (초광대역 시스템의 계층변조 기반 적응적 듀얼 홉 전송 기법)

  • Kim, Dae-Hwan;Song, Hyoung-Kyu;Cho, We-Duke
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.7C
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    • pp.443-450
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    • 2011
  • Recently, various transmission techniques for communication and broadcasting systems have been developed to meet the dramatically increasing requirement of consumers. Because UWB (Ultra-Wideband) is a wireless communication technique that supports high data rate with low power, it can satisfy the requirement and can be applied to various wireless communication services. The multi-band orthogonal frequency division multiplexing (MB-OFDM) system, one of UWB system, is the wireless communication system that satisfies the transmission characteristic for UWB and so it can be used for various wireless communication services. In this paper, we propose a scheme that uses hierarchical modulation which is applied in digital video broadcasting system at the source and adaptive modulation based on the channel quality at the relays. The simulation results have shown that the proposed scheme has both the advantages of the increased throughput by 33% and similar BER performance to conventional scheme.

Multiband Enhancement for DEMON Processing Algorithms (대역 분할 처리를 통한 데몬 처리 성능 향상 기법)

  • Cheong, Myoung Jun;Hwang, Soo Bok;Lee, Seung Woo;Kim, Jin Seok
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.2
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    • pp.138-146
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    • 2013
  • Passive sonars employ DEMON (Detection of Envelope Modulation on Noise) processing to extract propeller information from the radiated noise of underwater targets. Conventional DEMON processing improves SNR(Signal to Noise Ratio) characteristic by Welch method. The conventional Welch method overlaps several different time domain DEMON outputs to reduce the variance. However, the conventional methods have high computational complexity to get high SNR with correlated acoustic signals. In this paper, we propose new DEMON processing method that divides acoustic signal into several frequency bands before DEMON processing and averages each DEMON outputs. Therefore, the proposed method gathers independent acoustic signal faster than conventional method with low computational complexity. We prove the performance of the proposed method with mathematical analysis and computer simulations.

Transformation of 4-port Self-feedback Dual-band Bandpass Filter into 2-port (4단자 자기 귀환 방식 이중대역 대역통과 여파기의 2단자로의 변환)

  • Lim, Ji-Eun;Nam, Min-Hee;Choi, Han-Ol;Lee, Jae-Huyn
    • Journal of Satellite, Information and Communications
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    • v.5 no.2
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    • pp.25-28
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    • 2010
  • The need for multiband RF front-end in modern communication system is growing rapidly. For example, satellite system always uses a complex arrangement of frequency plans and consequently needs filters for each communication channel and it will be ideal to have a single filter module that does jobs of all those channel filters to reduce the size and payload of the system. In this paper, a new method to transform four-port self-feedback balanced dual-band bandpass filter into two-port is proposed. The two-port balanced dual-band bandpass filter which has baluns at the input and output ports and the fundamental frequency at 2.5 GHz and the first harmonic frequency at 5.7 GHz is fabricated and measured. Good agreement between measured and simulated results was achieved.

Implementation of Various FIR Filters using Constrained Least Square Criterion (제한된 최소 자승 오차 기준에 의한 다양한 FIR 필터 구현)

  • Hong, Seung-Eok;Kim, Joong-Kyu
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.10
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    • pp.175-185
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    • 1998
  • In this paper, we studied some design methodologies of typical FIR filters based on the peak-error constrained least square criterion which was first introducedd by Adams in 1991. This method is a mixed type of the classical least squared error method(LSM) and the so-called min-max error method (MMM). And by considering both the least squared error as well as the maximum error, the solution, i.e. the impulse response of the filter, can be found only when the restrictions on maximum gain, transition bandwidth, and the squared error are satisfied simultaneously under some trade-off conditions. We used the multiple exchange algorithms for optimization procedure and applied the design methodology to the cases of the multiband filter, the differentiator, and the Hilbert transformer by taking the balance of two design criteria into account. The results show that the peak-error constrained least weighted square error design method(PLEM) is superior in performance to the existing LSM and MMM from both the squared error and the maximum error standpoints. And it is verified that PLEM can be applied to not only the case of simple low pass filter, but also to various types of FIR filters.

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