COMPACT PLANAR ANTENNA HAVING TWO IDENTICAL PORTS AND TERMINALS

摘要

PROBLEM TO BE SOLVED: To hold the same polarized wave for the transmission path and the reception path of a terminal in the environment of radio communication network. SOLUTION: In a compact planar antenna being formed on a substrate having an annular slot 1B, the annular slot 1B is designed to function at a given frequency and located on the short circuit face of a line 2B through which power is fed to the annular slot of the planar antenna. A second line 2B' for feeding to the annular slot is located symmetrically to the first line 2B on the short circuit face of a line common to the first line 2B and the second line 2B'. Each line is provided with a port 4B, 4B' which is connected with a switching means 3B, 3B' such that power can be fed to the planar antenna through any one of two ports 4B and 4B'.