INTERFERING WAVE SUPPRESSION CIRCUIT, ANTENNA DUPLEXER, TRANSMISSION AND RECEPTION CIRCUIT, AND COMMUNICATION EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To solve the problem that a transmission frequency is leaked to the side of a reception circuit when the transmission frequency and a reception frequency are close to each other to some degree in a communication system for simultaneously transmitting and receiving in the whole or part of communication.

SOLUTION: This interfering wave suppression circuit to be used for a radio circuit for simultaneous transmission and reception is provided with: a first directional coupler 18 for receiving a signal of the transmission frequency, dividing the signal into two and outputting the resultant signals; and a second directional coupler 19 which receives a signal including the signal of the leaked component of the signal of the reception frequency and that of the transmission frequency to one input, inputs the signal of the transmission frequency from the one output of the first directional coupler 18 to the other input and combines and outputs the inputs. The signal of the leaked component of a transmission signal included in the signal inputted to one input of the second directional coupler 19 and the signal of the transmission frequency inputted to the other input of the second directional coupler 19 are adjusted to have substantially equal amplitude and antiphase.

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