A high-frequency composite component for use in a multi-frequency system, comprising first and second circuits connected in parallel, the first circuit having substantially infinite input impedance at a first frequency whereby said first frequency is passed by said second circuit, and the second circuit having substantially infinite input impedance at a second frequency whereby said second frequency is passed by said first circuit,
- wherein said first circuit includes a first phase shifter and a first trap circuit connected as a load of said first phase shifter, said first phase shifter providing said substantially infinite input impedance at said first frequency, and said first trap circuit providing substantially zero load impedance at said first frequency;
- and
- wherein said second circuit includes a second phase shifter and a second trap circuit connected as a load of said second phase shifter, said second phase shifter providing said substantially infinite input impedance at said second frequency, and said second trap circuit providing substantially zero load impedance at said second frequency,
- wherein said second circuit further includes an amplifier and a bandpass filter for said first frequency.