| 摘要 |
PROBLEM TO BE SOLVED: To surely exchange data indoors by radio and to prevent the appearance in the room from being damaged using a thin planar form. SOLUTION: A patch antenna 26 and a ground electrode 28 are provided through a ceramic substrate 24 and two microstrip ceramic antennas 20 capable of exchanging circularly polarized waves are point-symmetrically arranged on an insulated substrate 22 while turning the patch antennas 26 in the same direction and separating them just for the 3/4 wavelength of transmission/ reception frequency. Corresponding to the microstrip ceramic antennas 20, substrate side ground electrodes 30, 30... of a larger area are provided on both sides of the insulated substrate 22. The substrate side ground electrodes 30, 30... corresponding to two microstrip ceramic antennas 20 are not electrically connected each other. The substrate side ground electrodes 30, 30... and the ground electrodes 28 and 28 are electrically connected. The data are exchanged while appropriately switching these two microstrip ceramic antennas 20 and 20.
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