Double-loop antennas for a circularly polarized tilted beam

Kazuhide Hirose, Satoshi Okazaki, Hisamatsu Nakano

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

An antenna consisting of two concentric loops is analyzed using the method of moments. The antenna radiates a circularly polarized (CP) beam tilted from the direction normal to the antenna plane (the axial direction). First, an antenna with two feeds is analyzed. The configuration parameters are optimized in such a way that the inner and outer loops radiate CP axial and conical beams, respectively. These two radiation beams are then combined to form a CP tilted beam. It is found that the tilt angle is 25°, where the axial ratio and gain are 0.6 and 10 dB, respectively. Next, the phase between the two feeds is varied. Calculations show that the beam azimuth direction varies in a range of 360°. Finally, an antenna with a single feed is analyzed. The antenna shows radiation characteristics comparable to those for the two feeds. Further calculation reveals that a VSWR of 1.0 is obtained for another single feed using electromagnetic coupling. The VSWR remains less than 2 in the frequency bandwidth (of 2.5%) for a 1-dB gain-drop criterion. Within this bandwidth, the axial ratio is less than 3 dB.

Original languageEnglish
Pages (from-to)12-20
Number of pages9
JournalElectronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)
Volume86
Issue number12
DOIs
Publication statusPublished - 2003 Jul 17

Keywords

  • Circularly polarized antenna
  • Double loop antenna
  • Loop antenna
  • Method of moments
  • Tilted beam

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering

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