Monofilar archimedean spiral slot antennas

Kazuhide Hirose, Kazuo Nakayama, Hisamatsu Nakano

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


A monofilar Archimedean spiral is adopted as a circularly polarized slot radiator which is electromagnetically coupled to a feed line. Numerical analysis of the coupling between the slot and the feed line reveals that, when the slot arm length is properly chosen, a traveling-wave magnetic current is distributed along the slot, leading to the radiation of a circularly polarized wave. On the basis of this radiation mechanism, a spiral slot printed antenna fed by a triplate transmission line is experimentally designed to obtain a unidirectional radiation beam. It is found that an axial ratio of 0.6 dB is achieved, and that the spiral slot is matched to the transmission line with a VSWR of less than 1.5. An array antenna composed of 32 printed spiral slots is constructed, attaining a 5% bandwidth for a 3-dB axial ratio criterion. The formation of several tilted beams is also demonstrated.

Original languageEnglish
Pages (from-to)415-426
Number of pages12
Issue number3-4
Publication statusPublished - 1994 Jan 1
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Radiation
  • Electrical and Electronic Engineering


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