Title :
The effects of an upper dielectric layer on the radiation characteristics of a spiral antenna
Author :
Nakano, H. ; Okabe, Y. ; Mimaki, H. ; Yamauchi, J.
Author_Institution :
The Nakano Lab., Hosei Univ., Tokyo, Japan
Abstract :
An upper dielectric layer of thickness B/sub 2/ is applied to a spiral antenna printed on a dielectric substrate of thickness B/sub 1/ backed by a ground plane of infinite extent. The upper layer and the substrate are of finite extent and have the same dielectric constant. The antenna characteristics are calculated as a function of thickness B/sub 2/. As B/sub 2/ increases, the input impedance and axial ratio show oscillatory behavior with a periodicity of approximately /spl lambda//sub g//2. It is also found that the gain does not monotonically increase. An increase of 6.5 dB over the gain without the upper dielectric layer is obtained.
Keywords :
antenna radiation patterns; microstrip antennas; spiral antennas; antenna input impedance; axial ratio; dielectric constant; dielectric substrate; infinite ground plane; oscillatory behavior; printed antenna; radiation characteristics; spiral antenna; upper dielectric layer; Arm; Current distribution; Dielectric materials; Dielectric substrates; Finite difference methods; Frequency; Impedance; Spirals; Surface waves; Time domain analysis;
Conference_Titel :
Antennas and Propagation Society International Symposium, 2001. IEEE
Conference_Location :
Boston, MA, USA
Print_ISBN :
0-7803-7070-8
DOI :
10.1109/APS.2001.959417
