An antenna is mounted in a vehicle for receiving a radio wave of a specified wavelength, and an electronic device such as a meter device is mounted in the vehicle. The electronic device tends to generate radiation noise when being operated. To reduce reception of the radiation noise by the antenna, a passive conductor element is located between the antenna and the electronic device to reflect a part of the radiation noise. The passive element is away from the electronic device by a distance that is about multiple times of one-quarter of the specified wavelength and is about multiple times of one-half of the specified wavelength in length.