Journal of Sensor Science and Technology (센서학회지)

The Korean Sensors Society (한국센서학회)
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Design of A Broadband Bowtie Antenna for RF Spectral Measurements of Alfvén-wave in the KSTAR Tokamak

KSTAR 토카막의 Alfvén파 RF 스펙트럼 측정을 위한 광대역 보우타이 안테나 설계

  • Woo, Dong Sik (School of Electronics Engineering, Kyungpook National University) ;
  • Kim, Sung Kyun (School of Electronics Engineering, Kyungpook National University) ;
  • Kim, Kang Wook (School of Electronics Engineering, Kyungpook National University) ;
  • Choi, Hyun-Chul (School of Electronics Engineering, Kyungpook National University)
  • 우동식 (경북대학교 IT대학 전자공학부) ;
  • 김성균 (경북대학교 IT대학 전자공학부) ;
  • 김강욱 (경북대학교 IT대학 전자공학부) ;
  • 최현철 (경북대학교 IT대학 전자공학부)
  • Received : 2016.01.05
  • Accepted : 2016.01.25
  • Published : 2016.01.29
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Abstract

During KSTAR plasma experiments, torsional $Alfv\acute{e}n$ waves in the frequency of few GHz or below were detected. To understand this plasma waves during the crash of MHD instabilities, an RF spectrometer has been developed for detection of the radiated RF signals in the KSTAR Tokamak. It has the capability of broadband RF spectral measurement (50 ~ 400 MHz). To detect the broadband RF signals which are radiated from the KSTAR systems, a broadband antenna is the key feature of the RF spectrometer. In this paper, a broadband bowtie antenna for detection of $Alfv\acute{e}n$-waves in the KSTAR Tokamak is presented. Planar-type bowtie antenna is designed and fabricated on an FR4 substrate with thickness of 1.6 mm. The antenna consists of bowtie shaped balanced radiators and broadband planar balun. The antenna is designed to have an input impedance of 50 Ohm, and a taper-shaped balun is adopted for field and impedance matching between 50 Ohm transmission line to 110 Ohm feeding network of balanced radiators. The implemented antenna provides around -3 to 3 dBi of gain for the whole frequency band. The VSWR of the bowtie antenna is less than 12:1 over the frequency bandwidth of 50 to 2000 MHz.

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References

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