Antenna duplexer

摘要

An antenna duplexer has a transmission input terminal, a receiving output terminal, an antenna terminal in which a transmission output terminal and a receiving input terminal are used in common, a transmission filter having at least one resonance element set between the transmission input terminal and the transmission output terminal and coupled by a coupling element, a receiving filter having at least one resonance element set between the receiving output terminal and said receiving input terminal and coupled by a coupling element, and an impedance variable element connected to the resonance element of the transmission filter and the resonance element of said receiving filter respectively in parallel, wherein the frequency transfer characteristic of the transmission filter and the frequency transfer characteristic of the receiving filter are controlled by applying control signals and thereby changing the impedances of the impedance variable element.