Compact multisector antenna employing microstrip Yagi-Uda array antenna with common director elements

Multisector antennas are effective for high-speed wireless communications because they not only can provide a high gain with a simple configuration but also can reduce multipath fading and interference waves. However, multisector antenna have the problem that miniaturization is difficult because an antenna is needed in each sector. In this paper, a small dual-beam antenna configuration is proposed that shares director elements between two opposing microstrip Yagi-Uda arrays and a multisector configuration based on this antenna configuration. First, it is shown by analysis that an arbitrary conical beam width can be obtained with the microstrip Yagi-Uda array antenna with common director elements. It is also shown that undesired radiation can be reduced by terminating the nonactive feed elements in the microstrip Yagi-Uda array antenna with common director elements. Further, it is shown that planar six-sector antennas can be realized with a diameter of 2.27 wavelengths if three microstrip Yagi-Uda array antennas with common director elements are arranged in an equilateral triangle. The characteristics obtained are about 66 degrees of conical beam width and less than -25 dB of adjacent sector coupling. (c) 2005 Wiley Periodicals, Inc.