Dual-band phase offset line with required transmission phases at two operational frequencies

The paper presents analytical design methodology for realizing dual-band phase offset line using multi-section coupled lines. The circuit is designed to emulate a transmission line of 50 Ω characteristic impedance with two different arbitrary phases at the two frequencies. A prototype has been design at 1960 /3500 MHz that is used in dual-band Doherty power amplifier operating for CDMA and WiMAX applications.