Abstract: An antenna duplexer has an antenna terminal; a transmitting phase-shift circuit, one side of which is connected to the antenna terminal; a receiving phase-shift circuit, one side of which is connected to the antenna terminal; a transmitting filter connected to the other side of the transmitting phase-shift circuit and a transmitting terminal; and a receiving filter connected to the other side of the receiving phase-shift circuit and a receiving terminal; wherein the transmitting filter and/or the receiving filter is a composite filter, and the composite filter attains a characteristic having an attenuation pole at simultaneous transmission and reception time when transmission and reception are simultaneously performed, and controls respective impedances by the transmitting phase-shift circuit and the receiving phase-shift circuit to operate as a sharing unit and attains a characteristic where the attenuation pole is removed at non simultaneous transmission and reception time when transmission and reception

Abstract: An antenna duplexer has an antenna terminal;

Abstract: When the radio circuit apparatus is transmitting, the output signal of the first local oscillator 102 is inputted to the transmitted frequency converter 112 as well as to the frequency divider 104, and then the output signal of the frequency divider 104 is inputted to the modulator 111. The modulator 111 modulates the output signal of the frequency divider 104 with a base band signal. The output signal of the modulator 111 is inputted to the transmitted frequency converter 112, to be converted to the frequency of a transmitted signal by the output signal of the first local oscillator 102. When the radio circuit apparatus is receiving, the output signal of the low noise amplifier 121 is inputted to the first frequency converter 122 to be converted to the first intermediate frequency by the output signal of the first local oscillator 102.