Radio antenna device

Abstract

A radio antenna is disclosed with improvement in a radiation efficiency obtained by changing a directivity pattern of an antenna toward a direction not interfered by an obstacle and thus reducing radio wave interference by the obstacle. A whip antenna is connected to a transceiver unit in a radio set housing through a feeder line. A passive element is grounded to the radio set housing through a load impedance element. The whip antenna changes the horizontal directivity pattern in dependence upon the electromagnetic coupling with the passive element. The passive element operates as a wave director or a reflector for the whip antenna in accordance with the value of the load impedance element. When the passive element operates as a wave director, the radiation becomes much stronger in the direction toward the passive element. On the other hand, when the passive element operates as a reflector, the radiation in the direction away from the passive element becomes much stronger.

Dependencies are inferred from the claim text.