Patent ID: 7250910
Filing Date: 2007-07-31
Classification: H01Q

Abstract:
1. An antenna apparatus comprising: 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.