Abstract: Provided is an antenna device whose characteristics are enhanced (radio waves are efficiently emitted from an extended antenna) without need to place a communication unit that wirelessly communicates with the outside of a vehicle in close proximity to a loop structure of the vehicle, thus allowing a high flexibility of installation of the communication unit. An antenna device mounted on a vehicle includes a communication unit configured to wirelessly communicate with an outside of the vehicle, and a metal bracket configured to serve also as an extended antenna, and the communication unit includes a housing and a substrate-accommodated in the housing and on which a pattern antenna is formed, the metal bracket includes a first part fixed to the housing and a second part fixed to the vehicle.

Abstract: An antenna device includes a printed circuit board including a circuit configured to determine a position based on a navigation signal, and a dipole antenna element mounted on the printed circuit board and configured to receive the navigation signal. Further, the antenna device includes an L-shaped parasitic antenna element, wherein the dipole antenna element and a long-side element of the L-shaped parasitic antenna element are placed parallel to each other but at a position not in line with each other, and an end of a short-side element of the L-shaped antenna element is placed in close proximity to an end of the dipole antenna element.

Abstract: The use state of the seatbelt is warned in the start-warning mode during the specified start-warning period of time after the starting of the power source of the vehicle. The warning by the warning device is disabled when the specified start-warning period of time has lapsed after the power source starting (step S15). The warning device to warn the use state of the seatbelt are enabled for the specified period of time (step S17-S20) when the use state of the seatbelt detected by the seatbelt use-state detecting device changes during the operation of the vehicle power source (step S12). When the seatbelt is changed from its state of use to its state of non-use, the warning is conducted with the harder warning stimulation characteristic (steps S18, S19). Accordingly, there can be provided the seatbelt use-state warning device which can warn the driver properly.