Antenna apparatus utilizing minute loop antenna and radio communication apparatus using the same antenna apparatus

An antenna device apparatus comprising:

• a plurality of antenna devices;
• and
• a fourth switch device for selectively switching said plurality of antenna devices based on radio signals received by the plurality of antenna devices, and for connecting a selected antenna device to the feeding point,
• wherein said antenna device comprises:
• a dielectric substrate including a grounding conductor;
• a minute loop antenna provided to be electromagnetically close to said dielectric substrate, said minute loop antenna having a predetermined number N of turns and having a predetermined minute length, said minute loop antenna operating as a magnetic ideal dipole so that a magnetic current flows so as to cross said minute loop antenna when a predetermined metal plate is located closely to the antenna device;
• and
• at least one antenna element connected to said minute loop antenna, said at least one antenna element operating as a current antenna so that said at least one antenna element is top-loaded by said minute loop antenna and currents flow in both of said minute loop antenna and said at least one antenna element when said metal plate is located apart from the antenna device;
• wherein said antenna device further comprises at least one first capacitor connected to at least one of said minute loop antenna and said antenna element, said at least one capacitor series-resonates with inductances of said minute loop antenna and said antenna element,
• wherein one end of said antenna device is connected to a feeding point, and another end of said antenna device is connected to the grounding conductor of said dielectric substrate, and
• wherein said antenna device operates as a magnetic ideal dipole by said minute loop antenna when said metal plate is located closely to the antenna device, while said antenna device operates as a current antenna by said at least one antenna element when said metal plate is located apart from the antenna device.

A radio communication apparatus comprising:

• an antenna apparatus;
• and
• a radio communication circuit connected to said antenna apparatus,
• wherein said antenna apparatus comprises:
• a dielectric substrate including a grounding conductor;
• a minute loop antenna provided to be electromagnetically close to said dielectric substrate, said minute loop antenna having a predetermined number N of turns and having a predetermined minute length, said minute loop antenna operating as a magnetic ideal dipole so that a magnetic current flows so as to cross said minute loop antenna when a predetermined metal plate is located closely to the antenna apparatus;
• and
• at least one antenna element connected to said minute loop antenna, said at least one antenna element operating as a current antenna so that said at least one antenna element is top-loaded by said minute loop antenna and currents flow in both of said minute loop antenna and said at least one antenna element when said metal plate is located apart from the antenna apparatus;
• wherein said antenna apparatus further comprises at least one first capacitor connected to at least one of said minute loop antenna and said antenna element, said at least one capacitor series-resonates with inductances of said minute loop antenna and said antenna element,
• wherein one end of said antenna apparatus is connected to a feeding point, and another end of said antenna apparatus is connected to the grounding conductor of said dielectric substrate, and
• wherein said antenna apparatus operates as a magnetic ideal dipole by said minute loop antenna when said metal plate is located closely to the antenna apparatus, while said antenna apparatus operates as a current antenna by said at least one antenna element when said metal plate is located apart from the antenna apparatus.