| 摘要 |
PURPOSE: To improve the state of communication and to eliminate strain for incorporating an antenna in a water meter. CONSTITUTION: A waterwork meter 3 is provided in a meter box 1, which is set in the earth. A plate-shaped inverted-F antenna 8 is housed in a cap 7 of the meter box 1. The cap 7 is constituted of a resin material, whose relative dielectric constant is, e.g. 4. An earth conductor plate 10 is embedded in the lower surface of the cap 7, and a square radiator plate 11 is embedded in the inside. A conductor rod 14 shorts the earth conductor plate 10 and the radiator plate 11. A coaxial cable 9 electrically connects the ratio unit of the waterwork meter 3 and the plate-shaped inverted-F antenna. The surrounding length of the radiator plate 11 is determined at about 1/2 of the radiowave in the dielectric material constituting the cap 7. |
