1. Equiangular spiral antenna backed by a shallow cavity with absorbing strips
- Author
-
Nakano, H., Kikkawa, K., Iitsuka, Y., and Yamauchi, J.
- Subjects
Antennas (Electronics) -- Properties ,Time-domain analysis -- Methods ,Ultra wideband technology -- Equipment and supplies ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
When a conducting shallow cavity is placed behind an equiangular spiral to obtain a unidirectional beam, the inherent wideband characteristics of the spiral deteriorate. To restore the wideband characteristics, a ring-shaped absorbing strip (R-ABS) is placed under the spiral arms. Analysis of the equiangular spiral with the R-ABS is performed using the finitedifference time-domain method. It is found that the R-ABS successfully restores the wideband characteristics. Subsequently, the R-ABS is divided into two absorbing strips, each specified by an arc-angle [[phi].sub.ARC]. Analysis reveals that the radiation characteristics obtained using the R-ABS are reproduced when the arc-angle is greater than [[phi].sub.ARC] = 90[degrees]. Throughout this paper an extremely small cavity depth is selected for the analysis: 0.07 wavelength at the lower operating design frequency of 3 GHz. Index Terms--Absorbing strips, cavity, equiangular spiral, wideband characteristics.
- Published
- 2008