| 摘要 |
PROBLEM TO BE SOLVED: To provide a wireless smoke sensor having a range of electric wave that is not different from the conventional range even when the sensor is downsized.SOLUTION: In addition to a metal as a ground conventionally disposed on a printed board of a smoke sensor, a metallic insecticidal net is made to serve as the ground of an antenna, thereby securing the surface area of the ground. Therefore, the total surface area of the ground is kept even when the ground disposed on the printed board is decreased. Thus, even when the printed board is decreased, the range of electric wave can be kept. Therefore, the smoke sensor body can be downsized. |
