Patent ID: 6766149
Filing Date: 2004-07-20
Classification: H03H

Abstract:
A switching antenna duplexer sharing a single antenna between two systems using different transmitting fT(1), fT(2) and receiving fR(1), fR(2) frequencies respectively;wherein said frequencies of said two systems such that fT(1)T(2) and fR(1)R(2) when transmitting and receiving frequency bands of a first one of said two systems are represented by fT(1) and fR(1) respectively and transmitting and receiving frequency bands of a second one of said two systems are represented by fT(2) and fR(2); wherein a signal adapted to said first system and a signal adapted to said second system share an antenna terminal through a low pass filter and a high pass filter respectively; wherein a reception signal in said frequency band fR(1) inputted from said antenna is received through said antenna terminal and sent to a receiving-system terminal adapted to said first system through said low pass filter, a first parallel connection point and a separate filter, said first parallel connection point being a connection point between receiving and transmitting systems adapted to said first system, said separate filter having said frequency band fR(1) as its pass band and having a reflection coefficient the absolute value of which is not less than 0.8 in the frequency band fT(1) viewed from said first parallel connection point; wherein a transmission signal in said frequency band fT(1) is inputted to a transmitting-system adapted to said first system, and sent to said antenna terminal through a switching circuit, said first parallel connection point and said low pass filter, said switching circuit having a reflection coefficient the absolute value of which is not less than 0.8 in the frequency band fR(1) viewed from said first parallel connection point when said switching circuit is OFF; wherein a reception signal in said frequency band fR(2) inputted from said antenna is received through said antenna terminal and sent to a receiving-system terminal adapted to said second system through said high pass filter, a second parallel connection point and a second separate filter, said second parallel connection point being a connection point between receiving and transmitting systems adapted to said second system, said second separate filter having said frequency band fR(2) as its pass band and having a reflection coefficient the absolute value of which is not less than 0.8 in the frequency band fT(2) viewed from said second parallel connection point; wherein a transmission signal in said frequency band fT(2) is inputted to a transmitting-system adapted to said second system, and sent to said antenna terminal through a switching circuit, said second parallel connection point and said high pass filter, said switching circuit having a reflection coefficient the absolute value of which is not less than 0.8 in the frequency band fR(2) viewed from said second parallel connection point when said switching circuit is OFF.