Abstract: An antenna comprises a dielectric member, an antenna pattern formed on one surface of the dielectric member, and a ground pattern formed on the other surface of the dielectric member. A part or the whole of the antenna is implanted in a dielectric layer on the side from which a laser beam does not come in of an optical recording medium symmetrically having a metal layer reflecting the laser beam and the dielectric layer, thereby to provide a radio tag antenna structure for an optical recording medium which is simple, is small-sized, and can secure necessary reading performance.

Abstract: Either one or both of the antenna pattern and a ground pattern, which reflects a radiated radio wave radiated from the antenna pattern, are buried inside the glass substrate. As a result, it is possible to provide high-gain, low-loss glass antennas in which glass is used as their substrates.

Abstract: The present planar antenna include: a linear antenna element to which electric power is to be supplied and a loop-shaped parasitic antenna element placed in the vicinity of said linear antenna element, which are provided on one side of a dielectric substrate. This simple arrangement makes it possible to provide a planar antenna with good circular polarization characteristics.

Abstract: An antenna comprises a dielectric member, an antenna pattern formed on one surface of the dielectric member, and a ground pattern formed on the other surface of the dielectric member. A part or the whole of the antenna is implanted in a dielectric layer on the side from which a laser beam does not come in of an optical recording medium symmetrically having a metal layer reflecting the laser beam and the dielectric layer, thereby to provide a radio tag antenna structure for an optical recording medium which is simple, is small-sized, and can secure necessary reading performance.

Abstract: An antenna device is disclosed. An antenna such as a dipole antenna and a parallel feeder each formed of a conductor pattern are disposed on a dielectric plate. The connector is connected to the antenna through the parallel feeder. The parallel feeder has a length of an integral multiple of a half wavelength and has an even number of bending points between the connecter and the antenna.

Abstract: The electronic tag authentication device of the present invention authenticates the contents of an electronic tag attached to goods. The electronic tag authentication device comprises an antenna directivity change unit for changing the directivity of an antenna for transmitting/receiving electrical waves in order to authenticate the contents of the electronic tag.

Abstract: A disk tag reading device is a device for reading contents of an electronic tag attached to a disk. A holder which is inserted into a central hole of the disk configures an antenna for communicating with the electronic tag attached to the disk.

Abstract: An antenna comprises a dielectric member, an antenna pattern formed on one surface of the dielectric member, and a ground pattern formed on the other surface of the dielectric member. A part or the whole of the antenna is implanted in a dielectric layer on the side from which a laser beam does not come in of an optical recording medium symmetrically having a metal layer reflecting the laser beam and the dielectric layer, thereby to provide a radio tag antenna structure for an optical recording medium which is simple, is small-sized, and can secure necessary reading performance.