| 摘要 |
PCT No. PCT/SE94/00391 Sec. 371 Date Apr. 24, 1995 Sec. 102(e) Date Apr. 24, 1995 PCT Filed Apr. 29, 1994 PCT Pub. No. WO94/28593 PCT Pub. Date Dec. 8, 1994An improved antenna device for small size portable communication equipment comprising circuits (23) for transmitting and/or receiving radio signals as well as a chassis (25) and a feeding point (22) providing the electrical coupling of the antenna device to the communication equipment. The antenna device comprises a hollow helical antenna (6) fixed externally on the chassis and an antenna rod slidable through the helical antenna and being part of a straight radiator (1). The helical antenna (6) is of quarter-wave type and is coupled constantly via the feeding point (22) to the circuits (23). The straight radiator (1) is a quarter-wave radiator and the antenna device is provided with a switching device (2, 12, 13), which couples via the feeding point (22) the quarter-wave radiator (1) to the circuits (23) in parallel with the helical antenna (6) when the antenna rod is extended, while the switching device (2, 12, 13) substantially decouples the quarter-wave radiator from the circuits (23) and the feeding point (22) when the antenna rod is retracted. |
