Summary
International Symposium on Antennas and Propagation
2010
Session Number:2WC1
Session:
Number:2WC1-16
Design of a linearly-polarized radial line slot antenna with reflection-cancelling posts
Ken Saeki, Hideki Ueda, Jiro Hirokawa, Makoto Ando,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
A radial line slot antenna (RLSA) [1] is a slot array planar antenna. Generally, the RLSA is good for circular polarization where two orthogonal slots are spaced by a quarter guided wavelength as radiating unit and excited with equal amplitude and 90-degree phase difference, so that reflection from the two slots are cancelled out. Furthermore since the radiating units are arranged sequentially, very low reflection is realized at the feeding point. On the other hands, in the linearly-polarized (LP) RLSA [2], the linear polarization in the x-direction is obtained by the spacing of a half guided wavelength (d=λg/2) in the radial (ρ-) direction for alternative-phase excitation between two orthogonal slots as radiating unit. Since the slot pairs are arranged concentrically with the spacing of one guided wavelength, the reflecting waves are summed up in phase at the feeding point. Reflection cancellation is one of the most important assignments for the LP-RLSAs. To reduce the reflection, various methods have been investigated such as additional slot sets [3], beam-tilting design [4] and reflection-cancelling slots on the bottom plate [5]. However, each method has a problem such as complicated slot configuration, undesired radiation or beam tilt. We propose a LP-RLSA with a reflection cancelling post for each unit in the radial line. There is no beam tilt and no undesired radiation. In this paper, design procedure of the LP-RLSA and measured antenna characteristics of a prototype are shown.