A two-wire spiral antenna backed by a plane reflector with an unbalanced feed system

Kazuhide Hirose, Masamitsu Miyamoto, Hisamatsu Nakano

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


A novel unbalanced feed system, which achieves quasi-antiphase excitation without a balun circuit, is proposed for a two-wire spiral antenna backed by a conducting plane reflector. An inner spiral-wire end is fed from a coaxial line and the other inner spiral-wire end is short-circuited to the reflector. The antenna is analyzed using the method of moments. The radiation characteristics are found to be comparable to those of a conventional spiral antenna with antiphase excitation. The frequency bandwidth for a 3-dB axial-ratio criterion is 18% (20% for antiphase excitation), with a gain of approximately 8 dBi (8 dBi for antiphase excitation). The input impedance is almost constant at 170 - j30 ohms.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalElectronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)
Issue number4
Publication statusPublished - 2003 Apr
Externally publishedYes


  • Balun
  • Circularly polarized antenna
  • Method of moments
  • Spiral antenna
  • Wideband antenna

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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