FULL DUPLEX RADIO EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To prevent the S/N of a reception signal from being deteriorated caused by the reflected signal of a transmission signal on an antenna. SOLUTION: A transmission signal PTfrom a variable BPF (BandPass Filter) 4 is supplied to the antenna 2 through a circulator 5 and is transmitted as a radio wave. Part of the transmission signal PTis reflected at the antenna 2 due to the impedance mismatching of the antenna 2 and is coupled as the reflected signal PTRto a receiver 7 side through the circulator 5. Now, part of the transmission signal PTis distributed to a variable attenuation circuit 8 side through a distributor 10. The variable attenuation circuit 8 adjusts the transmission signal PTto a level approximately equal to the reflected signal PTR. A variable phase circuit 9 adjusts the phase of the transmission signal PTto approximately 180°to generate a correction signal PC. The correction signal PCis supplied to an addition circuit 11 to add the correction signal PCto the output signal (the reception signal) of the circulator 5 directed to the receiver side 7. Thus, the reflected signal PTRin the output signal is sufficiently canceled by the correction signal PC. COPYRIGHT: (C)2004,JPO&NCIPI