ANTENNA CHANGEOVER CIRCUIT FOR PORTABLE RADIO EQUIPMENT

PURPOSE:To reduce an insertion loss of the antenna changeover circuit by simplifying the antenna changeover circuit selecting a stationary antenna and an external antenna of the portable radio equipment. CONSTITUTION:When an external connector connects to a connector 9, a switch contact in the insid...

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Bibliographic Details
Main Authors HAGA HIROSHI, TATEISHI SUMIHIRO, ISHIBASHI FUJIO
Format Patent
LanguageEnglish
Published 12.03.1993
Subjects
ELECTRIC COMMUNICATION TECHNIQUE
ELECTRICITY
TRANSMISSION
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Summary:PURPOSE:To reduce an insertion loss of the antenna changeover circuit by simplifying the antenna changeover circuit selecting a stationary antenna and an external antenna of the portable radio equipment. CONSTITUTION:When an external connector connects to a connector 9, a switch contact in the inside of the connector 9 is thrown to the position shown in dotted lines, and a DC voltage +B from an external connector 14 is applied to a PIN diode 6 through a resistor 8, a high frequency current block coil 7, a transmission line 2, and a transmission line 1. The ON resistance of a diode 6 is small and a point (b) is short-circuited electrically when a DC current flows. When the point (b) reaches a low impedance, the high frequency unit connects to the external connector. When the external connector is removed from the portable telephone set, the switch contact in the inside of the connector 9 is restored to the state shown in solid lines and the point (b) reaches a high impedance. Simultaneously, the high frequency unit is connected to a stationary antenna via a capacitor 3 or the like.
Bibliography:Application Number: JP19910242372