| 摘要 |
This invention relates to an antenna apparatus which is compact in size and has a simple structure and two resonance characteristics. The antenna device of this invention comprises a conductive earth plate (2), a conductive radiation plate (1) disposed substantially parallel to the earth plate (2) through an insulator, a power feed line (3) having an earth conductor connected to the earth plate (2) and a non-grounded conductor connected to the radiation plate, and a passive line (4) connected to another junction (4c) spaced apart from a junction (3c) of the power feed line (3), and the earth conductor of passive line (4) is connected to the earth plate (2) while its non-grounded conductor is connected to the radiation plate (1). Since the passive line (4) operates as a short-circuit metal line at a low resonance frequency, a current distribution of about 1/4 wavelength exists on the radiation plate (1). Since the passive line operates as kept open at high resonance frequency, a current distribution of about 1/2 wavelength exists. <IMAGE> |
