Title :
Spiral antenna radiating a conical beam of circular polarization
Author :
Nakano, H. ; Oyanagi, H. ; Yamauchi, J.
Author_Institution :
Coll. of Eng., Hosei Univ., Tokyo, Japan
Abstract :
A two-arm spiral antenna excited in phase radiates a circularly polarized (CP) bidirectional beam. This bidirectional beam is transformed into a CP unidirectional beam using a conducting cavity as a reflector. The height of this cavity is chosen to be extremely small to realize a low-profile antenna: 0.077 wavelength at the lowest design frequency. The antenna characteristics, including the radiation pattern, VSWR, axial ratio, gain, and radiation efficiency when a ring-shaped absorbing strip is placed behind the outer spiral arms, are analyzed and discussed. It is found that a conical radiation pattern is obtained over a wide frequency range of 1: 2.9.
Keywords :
antenna radiation patterns; conical antennas; electromagnetic wave polarisation; reflector antennas; spiral antennas; CP; antenna radiation pattern; antenna reflector; bidirectional beam; circular polarization; conducting cavity; conical beam; low-profile antenna; spiral antenna; Antenna radiation patterns; Cavity resonators; Erbium; Spirals; Synthetic aperture sonar;
Conference_Titel :
Electromagnetics in Advanced Applications (ICEAA), 2010 International Conference on
Conference_Location :
Sydney, NSW
Print_ISBN :
978-1-4244-7366-3
DOI :
10.1109/ICEAA.2010.5652264
