To provide an antenna device capable of appropriately switching the antenna even when a matching circuit which causes a capacitive coupling is used.
An antenna device 1 includes: helical antennas 2 and 3; a radio circuit 4; high frequency switches 5, 11 and 12; and matching circuits 6 and 7. The helical antennas 2 and 3 are disposed being separated away from each other by a predetermined distance. When the high frequency switch 5 connects the radio circuit 4 and the helical antenna 2 therebetween, the high frequency switch 12 is opened and a channel between the radio circuit 4 and the helical antenna 3 is shut off. When the high frequency switch 5 connects the radio circuit 4 and the helical antenna 3 therebetween, the high frequency switch 11 is opened and the channel between the radio circuit 4 and the helical antenna 2 is shut off. With this, a power supply channel to an antenna which is not connected by the high frequency switch 5 is shut off.
| JPH11205206A | 1999-07-30 | |||
| JP2000068909A | 2000-03-03 | |||
| JPH08265235A | 1996-10-11 | |||
| JP2006174220A | 2006-06-29 |
| WO2008010299A1 | 2008-01-24 |
Katsumi Taguchi
Shinichi Mizuta
Itaya Masayuki