| 摘要 |
PURPOSE:To arrange an antenna inconspicuously and to improve the safety by attaching a radio unit, where crime preventing and disaster preventing sensors and a transmitter are stored in the same enclosure, to building materials with which the antenna is brought into contact. CONSTITUTION:A dipole antenna 2a as an antenna body is formed on the lower face of building materials 1 of ceiling materials by conductive materials 2. A radio unit 4 where the crime preventing sensor and the transmitter are stored in the same enclosure is attached to the lower face of building materials 1a which is a part of ceiling materials constituting a ceiling 6. A hole is provided in a part of building materials 1a on the upper face of the radio unit 4, and an antenna line 3 which connects a high frequency output part of the radio unit 4 and a feeding part of the dipole antenna 2a is inserted through this hole 5. The dipole antenna 2a is arranged on a rear side B of the ceiling, and the radio unit 4 is arranged on the side of a living space A.
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