Abstract: An antenna device includes a ground plate and an antenna element. The ground plate is a conductor member with a flat rectangular shape. The antenna element is a conductor member having a feed point electrically connected to a feeder line. A length of the ground plate in a predetermined direction is shorter than a target wavelength that is a wavelength of a radio wave to be transmitted or received. The ground plate is connected to a grounding cable at a connection position on the ground plate. The connection position is shifted from an edge of the ground plate by an odd multiple of ¼ of the target wavelength.

Abstract: An antenna device includes a ground plate which is a flat plate-shaped conductor member, an opposing conductive plate which is a flat plate-shaped conductor member installed at a predetermined distance from the ground plate and is electrically connected to a power supply line, and a plurality of short-circuit pins for electrically connecting the opposing conductive plate and the ground plate. One end of a plurality of short-circuit pins extends to a conductive plate plane, which is a plane including the opposing conductive plate, and the other end of the plurality of short-circuit pins extends to the ground plate plane, which is a plane including the ground plate. One or more of the plurality of short-circuit pins connect the opposing conductive plate and the ground plate.

Abstract: A portable device transmits wirelessly pilot signals of a plurality of frequencies sequentially at predetermined time intervals. Upon receiving the pilot signals, the in-vehicle device determines whether a slope of a straight line obtained by linearly approximating a time and a reception signal strength of each of the pilot signals is equal to or less than a predetermined slope threshold value. In response to a predetermined allowable condition including the slope being determined to be equal to or less than the slope threshold value being satisfied, a distance between the portable device and the in-vehicle device obtained by a distance measurement process is specified as a high reliability distance. In response to the predetermined allowable condition being not satisfied, the distance obtained by the distance measurement process is prevented from being specified as the high reliability distance or the distance measurement process is prevented from being executed.

Abstract: A vehicle system includes a portable terminal and an in-vehicle device. The portable terminal is configured to perform short-range wireless communication. The in-vehicle device is configured to locate the portable terminal based on a reception strength. The portable terminal includes a transmission unit configured to change a channel among channels. A reception strength selection unit of the in-vehicle device is configured to select a particular number of reception strengths for consecutive ones of the channels. A terminal locator unit of the in-vehicle device is configured to prioritize a largest reception strength to locate the portable terminal based on the reception strength. An upper limit of the particular number is set to be higher as an interval for transmitting information from the antenna to the in-vehicle device is shorter, and a lower limit of the particular number is set based on a multipath reduction effect.

Abstract: An antenna device includes a ground plate and an antenna element. The ground plate is a conductor member with a flat rectangular shape. The antenna element is a conductor member having a feed point electrically connected to a feeder line. A length of the ground plate in a predetermined direction is shorter than a target wavelength that is a wavelength of a radio wave to be transmitted or received. The ground plate is connected to a grounding cable at a connection position on the ground plate. The connection position is shifted from an edge of the ground plate by an odd multiple of ¼ of the target wavelength.

Abstract: An antenna device includes a ground plate which is a flat plate-shaped conductor member, an opposing conductive plate which is a flat plate-shaped conductor member installed at a predetermined distance from the ground plate and is electrically connected to a power supply line, and a plurality of short-circuit pins for electrically connecting the opposing conductive plate and the ground plate. One end of a plurality of short-circuit pins extends to a conductive plate plane, which is a plane including the opposing conductive plate, and the other end of the plurality of short-circuit pins extends to the ground plate plane, which is a plane including the ground plate. One or more of the plurality of short-circuit pins connect the opposing conductive plate and the ground plate.

Abstract: A vehicle system includes a portable terminal and an in-vehicle device. The portable terminal is configured to perform short-range wireless communication. The in-vehicle device is configured to locate the portable terminal based on a reception strength. The portable terminal includes a transmission unit configured to change a channel among channels. A reception strength selection unit of the in-vehicle device is configured to select a particular number of reception strengths for consecutive ones of the channels. A terminal locator unit of the in-vehicle device is configured to prioritize a largest reception strength to locate the portable terminal based on the reception strength. An upper limit of the particular number is set to be higher as an interval for transmitting information from the antenna to the in-vehicle device is shorter, and a lower limit of the particular number is set based on a multipath reduction effect.

Abstract: A portable device transmits wirelessly pilot signals of a plurality of frequencies sequentially at predetermined time intervals. Upon receiving the pilot signals, the in-vehicle device determines whether a slope of a straight line obtained by linearly approximating a time and a reception signal strength of each of the pilot signals is equal to or less than a predetermined slope threshold value. In response to a predetermined allowable condition including the slope being determined to be equal to or less than the slope threshold value being satisfied, a distance between the portable device and the in-vehicle device obtained by a distance measurement process is specified as a high reliability distance. In response to the predetermined allowable condition being not satisfied, the distance obtained by the distance measurement process is prevented from being specified as the high reliability distance or the distance measurement process is prevented from being executed.