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.
|ジャーナル||Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)|
|出版ステータス||Published - 2003 4 1|
ASJC Scopus subject areas
- Computer Networks and Communications
- Electrical and Electronic Engineering