| 摘要 |
PROBLEM TO BE SOLVED: To inhibit the use of portable telephones in a specific area and to increase speech communication sensitivity, conversely by selectively switching an output terminal of an amplifier which radiates interference waves in a specific area, with internal antennas for a potable telephone or with an external antenna. SOLUTION: An interference wave oscillation source 1 sends an interference wave that disenables the use of a portable telephone, while an amplifier 2 amplifies a signal so that it can be radiated within a specific area 12 on a relatively small scale, such as in a tearoom and in a train. An output terminal of the amplifier 2 is connected to switched terminals 7b respectively via matching devices 3 to 6. An external antenna 17 for allowing a portable telephone to function satisfactorily is installed on an external area. The antenna 17 is connected to switched terminals 7a of a switch 7 via a booster 18. Output terminals 7c of the switch 7 are connected to internal antennas 13 to 16. The switch 7 is switched to the terminals 7b side, in order to inhibit a portable telephone and is switched to the terminal 7a side for enhancing speech communication sensitivity. |
