• Title/Summary/Keyword: directional gain

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Design of Ultrawide Band Monopole Antenna (광대역 모노폴 안테나 설계)

  • 이종필;박성욱
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2001.11a
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    • pp.136-139
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    • 2001
  • In this paper, we propese a novel wide band printed monopole antenna called the staircase bow-tie monopole antenna (SBMA). We apply an extraordinarr method for an impedance matching to conventional bow-tie monopoles. So we get the SBMA with a very wide band. Our antenna is smaller than a quarter wavelength in size but provides a 2:1 VSWR bandwidth of about 77.8%. An antenna gain and a radiation pattern are about 1.7dBi and omni-directional at 1.7 GHz, respeotively.

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Charge/Discharge Mode Conversion Method of Bi-directional Soft-switching Converter with High Voltage Gain (고승압 소프트스위칭 양방향 컨버터의 충방전 모드전환 기법)

  • Kwon, Minho;Jeong, Heonsoo;Choi, Sewan
    • Proceedings of the KIPE Conference
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    • 2012.07a
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    • pp.185-186
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    • 2012
  • 본 논문에서는 고승압 소프트스위칭 양방향 컨버터의 스위칭 모드절환 시점을 제안하여 전류의 불연속 구간이 발생되지 않는 방법을 소개하여 일반적인 부스트 컨버터와 같이 일반적인 제어 알고리즘을 적용 가능함을 검증하였고 시뮬레이션 및 실험을 통해 타당성을 검증하였다.

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The Asymptotic Throughput and Connectivity of Cognitive Radio Networks with Directional Transmission

  • Wei, Zhiqing;Feng, Zhiyong;Zhang, Qixun;Li, Wei;Gulliver, T. Aaron
    • Journal of Communications and Networks
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    • v.16 no.2
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    • pp.227-237
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    • 2014
  • Throughput scaling laws for two coexisting ad hoc networks with m primary users (PUs) and n secondary users (SUs) randomly distributed in an unit area have been widely studied. Early work showed that the secondary network performs as well as stand-alone networks, namely, the per-node throughput of the secondary networks is ${\Theta}(1/\sqrt{n{\log}n})$. In this paper, we show that by exploiting directional spectrum opportunities in secondary network, the throughput of secondary network can be improved. If the beamwidth of secondary transmitter (TX)'s main lobe is ${\delta}=o(1/{\log}n)$, SUs can achieve a per-node throughput of ${\Theta}(1/\sqrt{n{\log}n})$ for directional transmission and omni reception (DTOR), which is ${\Theta}({\log}n)$ times higher than the throughput with-out directional transmission. On the contrary, if ${\delta}={\omega}(1/{\log}n)$, the throughput gain of SUs is $2{\pi}/{\delta}$ for DTOR compared with the throughput without directional antennas. Similarly, we have derived the throughput for other cases of directional transmission. The connectivity is another critical metric to evaluate the performance of random ad hoc networks. The relation between the number of SUs n and the number of PUs m is assumed to be $n=m^{\beta}$. We show that with the HDP-VDP routing scheme, which is widely employed in the analysis of throughput scaling laws of ad hoc networks, the connectivity of a single SU can be guaranteed when ${\beta}$ > 1, and the connectivity of a single secondary path can be guaranteed when ${\beta}$ > 2. While circumventing routing can improve the connectivity of cognitive radio ad hoc network, we verify that the connectivity of a single SU as well as a single secondary path can be guaranteed when ${\beta}$ > 1. Thus, to achieve the connectivity of secondary networks, the density of SUs should be (asymptotically) bigger than that of PUs.

SLIP CONTROLLER DESIGN FOR TRACTION CONTROL SYSTEM

  • Jung, H.;Kwak, B.;Park, Y.
    • International Journal of Automotive Technology
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    • v.1 no.1
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    • pp.48-55
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    • 2000
  • Two major roles of the traction control system (TCS) are to guarantee the acceleration performance and directional stability even in extreme road conditions, under which average drivers may not control the car properly. Commercial TCSs use experiential methods such as lookup table and gain-scheduling to achieve proper performance under various road and vehicle conditions. This paper proposes a new slip controller which uses the brake and the throttle actuator simultaneously. To avoid measurement problems and to get a simple structure, the brake controller and the throttle controller are designed using Lyapunov redesign method and multiple sliding mode control respectively. Through the hybrid use of brake and throttle controllers, the vehicle is insensitive to the variation of the vehicle mass, brake gain and road condition and can achieve the required acceleration performance. The proposed method is validated with simulations based on 15 DOF passenger car model.

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Design of a low-profile antenna for Satellite Digital Audio Radio Systems(SDARS) (유전자 알고리즘을 이용한 Satellite Digital Audio Radio System Antennas 개발)

  • Kim, Yong-Jin;Kim, Sang-Uk;Kim, Jin-Hwan;Kim, Yong-Geun;Kim, Young-Bong
    • Proceedings of the KIEE Conference
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    • 2007.11c
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    • pp.179-182
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    • 2007
  • The Design and Optimization of a low-profile antenna for the Satellite Digital Audio Radio System(SDARS) using a Non-Dominated Sorting Genetic Algorithm(NSGA) is presented. a fairly omni-directional elevation gain pattern over 60 degrees < q <60 degrees are obtained. The average value of the LCP gain pattern is approximately 2 dBic. The heights of the antennas are less than 0.251. The cross polarized signal level is approximately 12 dBic less than the co-polarized signal level.

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Cavity-backed Two-arm Spiral Antenna with a Ring-shaped Absorber for Partial Discharge Diagnosis

  • Kim, Han-Byul;Hwang, Keum-Cheol;Kim, Hyeong-Seok
    • Journal of Electrical Engineering and Technology
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    • v.8 no.4
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    • pp.856-862
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    • 2013
  • A cavity-backed two-arm spiral antenna for partial discharge diagnosis is presented. The proposed antenna consists of a two-arm Archimedean spiral, a tapered microstrip balun as spiral antenna feed, and a ring-shaped absorber-loaded cavity. The Archimedean spiral antenna is designed for the operating frequency band of 0.3 GHz to 1.5 GHz and fed by the tapered microstrip balun. The cavity is utilized to transform the bidirectional beam into a unidirectional beam, thereby enhancing gain. The ring-shaped absorber is stacked in the cavity to reduce the reflected waves from the cavity wall. The proposed antenna is designed and simulated using CST Microwave Studio. A prototype of the proposed antenna is likewise fabricated and tested. The measured radiation patterns are directional to the positive z-axis, and the measured peak gain is 8.13 dBi at a frequency of 1.1 GHz.

A Superconducting $Y_1Ba_2Cu_3O_{7-\delta}$ Square Spiral Microstrip Antenna

  • Jung, Sung-H.;Song, Ki-Y.
    • Progress in Superconductivity
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    • v.2 no.1
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    • pp.51-55
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    • 2000
  • A $Y_1Ba_2Cu_3O_{7-\delta}$ square spiral microstrip antenna (YBCO antenna) was epitaxially grown on a $LaAlO_3$ substrate by laser ablation. Also fabricated was a gold square spiral microstrip antenna (gold antenna) having the same structure as that of the YBCO antenna in order to compare the properties of both antennas. Both the YBCO antenna and the gold antenna were operated in Ku (12-18 GHz) band, and their properties such as the return loss, SWR, power gain, and radiation patterns were investigated at 77 K. The return loss below -10 dB was obtained in two frequency ranges, i.e., 14.05-14.90 GHz, and 16-18 GHz for the YBCO antenna at 77 K (YBCO superconducting antenna), and in the frequency range of 15.05-17.60 GHz for the gold antenna at 77 K. The SWR bandwidths are 0.85 GHz and 2 GHz for the YBCO superconducting antenna, and 2.55 GHz for the gold antenna at 77 K. The gain improvement of the superconducting YBCO antenna over the gold antenna at 77 K was about 10 dB in the frequency range of 16 GHz to 18 GHz. The radiation patterns show the YBCO superconducting antenna has the omni-directional property of a spiral antenna.

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Analysis and Design of a Spiral Antenna using Moment Method (모먼트법을 이용한 스파이럴 안테나의 해석 및 설계)

  • 한정세;이갑수;박병우
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.5
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    • pp.857-871
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    • 1994
  • In this paper, six kinds of spiral antenna, a combination of two types of spiral arm-width and three types of spiral curvature are analyzed by using moment method. Dividing spiral arms into N sections, the current distribution is calculated by Galerkin`s method. The radiation pattern and the antenna gain are derived from antenna currents. All os the six spiral antenna have amni-dirctional and wide-band characteristics, although the antenna gain changes within +_ 5dB bound for operating range(600MHz-2GHz). The variation of antenna`s gain is caused by the return loss in connection the Balun to the antenna. Simulation and experimental results on the radiation pattern also show spiral antennas have omni-directional and wide-band characteristics.

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Dual-Band Circle Microstrip Patch Antenna with Parasitic Patch (기생 패치 면을 갖는 이중 대 역 원형 마이크로스트립 패치 안테나)

  • Noh Seung-Jin;Shin Heai-Young;Kim Young-Sang;Kim Nam-Soo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.7 s.110
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    • pp.665-672
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    • 2006
  • In this paper, we propose and fabricate the dual-band microstrip patch antenna with parasitic patch for S-DMB(Satellite-Digital Multimedia Broadcasting) and ITS (Intelligent Transport System) services. The measured - 10 dB bandwidth and the minimum return loss is 300 MHz and - 27 dB for S-DMB, 600 MHz and -17 dB for ITS, respectively. It is noticed that the measured and simulated results are agreed well. The S-DMB antenna has conical beam pattern in the vertical plane and has omni-directional beam pattern in the horizontal plane. The conical beam pattern has the maximum gain about 4.2 dBi when ${\theta}$ is $45^{\circ}$ at the center frequency of 2.6 GHz. The ITS antenna has directional beam pattern in the vertical plane that has maximum gain about 6.4 dBi when ${\theta}$ is $0^{\circ}$ at the center frequency of 5.8 GHz.

Millimeter-wave directional-antenna beamwidth effects on the ITU-R building entry loss (BEL) propagation model

  • Lee, Juyul;Kim, Kyung-Won;Kim, Myung-Don;Park, Jae-Joon;Yoon, Young Keun;Chong, Young Jun
    • ETRI Journal
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    • v.42 no.1
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    • pp.7-16
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    • 2020
  • Assuming omnidirectional antenna reception, the ITU-R recently developed a new propagation model on building entry loss (BEL) for 5G millimeter-wave frequency sharing and compatibility studies, which is a simplified outdoor-to-indoor path loss model. Considering the utilization of high-gain narrow-beamwidth beamforming, the omnidirectional-based ITU-R BEL model may not be appropriate to predict propagation characteristics for directional beamforming scenarios. This paper studies the effects of beamwidth on the ITU-R BEL model. This study is based on field measurements collected with four different beamwidth antennas: omnidirectional, 10° horn, 30° horn, and 60° horn. The measurement campaigns were conducted at two types of building sites: traditional and thermally efficient buildings. These sites, as well as the measurement scenarios, were carefully chosen to comply with the ITU-R BEL measurement guidelines and the ITU-R building types. We observed the importance of accurate beam alignment from the BEL variation range. We were able to quantify the beamwidth dependency by fitting to a model that is inversely proportional to the beamwidth.