Patent attributes
A cutout portion through which one end side of a U-shaped portion of the antenna passes is cut deeper than a preset passing position where the U-shaped portion passes through the cutout portion. Further, an open dimension of a through hole through which the other end side of the U-shaped portion passes is substantially twice an outer diameter dimension of the U-shaped portion. When the U-shaped portion is passed through the through hole at the preset passing position, the U-shaped portion passes through the substantial center of the through hole. When error arises in the retention position of the antenna and the fixing position of the base plate, the U-shaped portion is displaced inside the cutout portion and the through hole, and the above error is absorbed.